Blog details

A concrete takeoff is the process of measuring every concrete-related quantity off a set of drawings — areas, volumes, linear metres and counts — before you price anything. The estimate is what happens next: you attach material rates, labour hours, plant, overhead and margin to those quantities to arrive at a number you can stand over. Takeoff answers how much. The estimate answers how much will it cost. The bid is what you send.

Most guides on this subject stop at "length × width × depth." That's the easy part. The money is lost in the parts nobody writes down: the eighth of an inch you didn't allow on the subgrade, the 840 linear feet of saw cutting that never made it onto the sheet, the short-load fee on the bollard bases, and the overhead you forgot to recover.

This guide walks the whole job — drawing to bid — with the formulas in both imperial and metric, one worked example carried the full way through, and every industry figure sourced so you can check it yourself.

Watch it done first

Concrete Takeoff & Estimate: Full Walkthrough — checking calibration, setting up groups, area measurements with deductions, applying depth for volume, saw cuts, counts, annotations, and exporting marked-up plans.

If you'd rather read, everything in the video is written out below.

Takeoff vs. estimate vs. bid — the distinction that costs people money

These three words get used interchangeably on site, and it causes real confusion when a GC asks for one and you send another.

A perfect takeoff with a bad estimate loses money. A bad takeoff makes the estimate irrelevant no matter how good your rates are. Both have to be right. If you want the general version of this before the concrete-specific detail, we've covered what a quantity takeoff actually is separately.

Why concrete punishes takeoff errors more than most trades

Concrete is unforgiving because the quantity is derived from a depth you can't see on a plan view, and small depth errors scale across a large area.

The National Ready Mixed Concrete Association puts a number on it:

"A 1/8-inch difference in a 4-inch thick slab results in a shortage of 3 percent (1 yd³ in a 32-yd³ order)." — NRMCA, CIP 8: Discrepancies in Yield

NRMCA's own metric statement of the same rule is 3 mm on a 100 mm slab. Three millimetres of subgrade tolerance is a 3% shortfall. That is not a rounding error — that's the last truck.

And the margin you're protecting is thin. The Construction Financial Management Association's 2025 benchmarker, covering 1,558 contractors, puts specialty trade contractors at 7.7% net income before tax, with direct costs running at 74.2% of revenue (CFMA, FY2024 data). Do the arithmetic: a 10% quantity error on your direct costs moves 7.4 points of revenue. That is your entire year's profit on the job.

Step 1: Get the right drawings, then check the scale

Before you measure a single thing, confirm the drawing is calibrated. This is the step people skip and the one that invalidates everything downstream.

Most takeoff tools default to a standard scale — 1:100 is typical on metric drawings. If the drawing was issued at 1:50, or scaled to fit an A3 sheet, every measurement you take is wrong by a constant factor and nothing on the page will look obviously off.

How to check it:

1. Find a known length on the drawing — a stated dimension string is ideal.

2. If there's no dimension, use something you know the real-world size of. A standard car parking space is a good one: roughly 2.4–2.5 m (8 ft) wide and 4.8–5.0 m (16 ft) long.

3. Measure it. If a car space comes back as 1 m or 10 m, stop and recalibrate.

4. Re-check the scale on every sheet, not just the first one. Details and sections are frequently at a different scale to the general arrangement.

   
   

This is exactly the sanity check demonstrated at the start of the video — there was no dimension string on the paving plan, so the car spaces became the reference.

Also gather before you start: the general arrangement, all relevant sections and details, the specification (for mix design, slab thickness, mesh or rebar grade, joint spacing and finish), and any soil or level information. If the specification isn't in front of you, you're guessing at thickness — and thickness is the whole job.

Step 2: Set up your groups and categories before you measure

This sounds like housekeeping. It is actually the difference between a takeoff you can defend and a pile of numbers.

Structure your measurements by the way you buy and build the work, not by the order you happen to trace it:

• 100 mm paving (4 in slab)

• 150 mm slab (6 in slab)

• Strip footings

• Formwork — edge

• Saw cuts

• Bollard bases

Each group gets its own colour on the drawing. Two things fall out of this immediately. First, when the GC queries a quantity, you can isolate the exact measurement rather than re-doing the whole sheet. Second, you can present the takeoff to your own crew as a set of coloured, marked-up plans — which is worth more on site than any spreadsheet.

Build these as templates. If you do formwork, structural and flatwork repeatedly, save the group structure once and load it on every job. The setup time collapses to zero from the second job onwards. If you're bidding work where the GC issues a bill of quantities, mirror their structure — it makes reconciliation trivial and queries far easier to answer.

Step 3: Measure the areas — and deduct what isn't yours

Trace the outline of each concrete area with a polygon or rectangle tool. The technique matters less than the discipline around it:

• Deduct openings, planted areas, and anything you're not pouring. A large central void that stays in your area measurement is money you've given away in the bid — or, if you win, concrete you've ordered and can't place.

• Split by thickness, not by shape. If a yard is 100 mm generally but 150 mm in the truck turning area, those are two separate measurements. They will be priced differently, poured differently, and reinforced differently.

• Watch for thickenings and turn-downs. Perimeter thickened edges, haunches under walls, and pier caps sit under the same plan-view outline as the slab. They are extra volume and they are the single most-missed item in flatwork takeoffs.

Working faster: learn your tool's keyboard shortcuts, particularly pan-and-zoom. Holding the space bar to drag around a large drawing while tracing sounds trivial; over a full day of takeoff it's the difference between four sheets and eight — you can watch it done one-handed throughout the walkthrough video.

Step 4: Turn area into volume

Here are the formulas. Metric readers get the easier deal.

A note on the two columns. Throughout this guide the imperial and metric examples are parallel jobs, not conversions of each other. A 4 in slab is 101.6 mm and a 100 mm slab is 3.94 in, so the two columns differ by about 1.6% by design. Work in the units your drawings and your supplier use, and read down one column.

Slabs and paving

The imperial shortcut some estimators use — "one cubic yard covers 81 SF at 4 inches" — is the same maths. 4,580 ÷ 81 = 56.5 CY. (Inch Calculator)

Footings, strip foundations, curbs

Volume = Length × Width × Depth (÷ 27 if you're working in feet)

• Imperial: 100 LF × 2 ft × 1 ft = 200 ft³ ÷ 27 = 7.4 CY

• Metric: 30 m × 0.6 m × 0.3 m = 5.4 m³

Walls

Volume = Length × Height × Thickness (÷ 27 for feet)

• Imperial: 40 ft × 8 ft × 0.667 ft (8 in) = 7.9 CY

• Metric: 12 m × 2.4 m × 0.2 m = 5.76 m³

Circular piers, columns, bollard bases

Volume = π × radius² × height

• Imperial: 18 in dia × 4 ft deep = π × 0.75² × 4 = 7.07 ft³ ÷ 27 = 0.26 CY each

• Metric: 450 mm dia × 1.2 m deep = π × 0.225² × 1.2 = 0.19 m³ each

Stairs

Treat each step as a triangular prism — (rise × run ÷ 2) × width — sum them, then add the throat slab underneath separately. The throat is where stair pours run short. Five steps at 7 in rise × 11 in run × 4 ft wide is only 0.20 CY of steps; the slab under them is often twice that again.

The thickness-to-volume cheat sheet

Pin this up. Imperial, cubic yards per 100 SF:

Metric needs no table: m³ per 100 m² = thickness in mm ÷ 10. A 100 mm slab is 10 m³ per 100 m². A 150 mm slab is 15 m³ per 100 m².

Step 5: Add your waste factor — 4% to 10%, and know which end you're on

Neat volume off the drawing is never what you order. The NRMCA guidance is explicit:

"Quantity of concrete ordered should be 4% to 10% more than an estimate calculated from the plan dimensions to account for contingencies." — NRMCA, CIP 31: Ordering Ready Mixed Concrete

Where you sit in that band is not arbitrary. NRMCA's own guidance gives you the rule:

"Repetitive operations and slip form placement permit more accurate estimates of the amount of concrete that will be needed. Sporadic operations involving a alternating placement in slabs, footings, walls, and as incidental fill around pipes will require a bigger allowance for contingencies." (sic) — NRMCA, CIP 8

In practice:

• Low end (4–5%): large repetitive pours, well-formed, screeded subgrade, tight thickness control, chute or pump direct.

• High end (8–10%): sporadic work, footings on rough or hand-dug subgrade, lots of small elements, uneven excavation, formwork that may deflect.

Use a different factor per pour type on the same job. The worked example later applies 5% to the main yard slab and 10% to twelve small bollard bases, because they are different placement operations with different risk. A single blanket percentage across a whole takeoff is the lazy version and it is wrong in both directions at once.

NRMCA also notes hardened concrete can occupy around 2% less volume than the freshly mixed material, from air content reduction, settlement, bleeding and shrinkage. That 2% is baked into why the floor of the range is 4% and not zero.

Don't over-order either. The rule of thumb from Concrete Network is sound: "A 20 cubic yard order with 1 cubic yard left over is a good order." That's 5%.

The short-load trap

This is the bit that turns a small quantity error into a big cost. Truck mixers carry 8–12 CY — that's 6–9 m³ (NRMCA CIP 31, which states the metric range as 5–9 m³). Order under a full load and you pay for it:

Run the sequence: an eighth of an inch of subgrade tolerance costs you 3% of volume, 3% on a 32 CY order is one cubic yard short, one cubic yard short means a second delivery, and the second delivery is a short load. The fee for the mistake is larger than the concrete you forgot.

Step 6: Take off the linear items and the counts

Volume is only one of four measurement types on a concrete job. Miss the other three and the takeoff is incomplete no matter how good the cubes are.

Linear — saw cuts and joints

Joint quantity is fully determined by the specification, so there's no excuse for guessing. NRMCA's guidance (CIP 6):

• Spacing: 24 to 36 times the slab thickness. For a 100 mm / 4 in slab that's about 3 m / 10 ft, and joint spacing should be limited to a maximum of 4.5 m / 15 ft.

• Depth: at least ¼ of slab thickness, and never less than 25 mm / 1 in.

• Timing: early-entry dry-cut 1–4 hours after finishing; conventional saw cut within 4–12 hours.

The quantity surprises people. A 30 m × 15 m yard at a 3 m grid takes 9 cuts across at 15 m and 4 cuts along at 30 m — 255 linear metres. The parallel imperial job, 98 ft × 50 ft on a 10 ft grid, comes to 842 LF. On a slab of barely 420 m². That is a real, priceable, entirely forgettable line item.

Linear — formwork, measured per face

Formwork is quantified as contact area — the surface the concrete actually touches. Imperial estimators call it SFCA (square feet of contact area) (SJ Civil).

The error that costs money: a wall is formed on two faces. A 12 m × 2.4 m wall isn't 28.8 m² of formwork, it's 57.6 m². A strip footing formed both sides is double its run. Missing the ×2 is one of the most common single-line errors in the trade.

One practical exception: shallow edge forms — a 100 mm or 4 in slab edge — are conventionally taken and priced in linear metres or linear feet rather than contact area, because the labour is driven by setting the line and level, not by the strip of ply. Anything with real height gets measured as area. Whichever you use, be consistent, and say which on the quote.

The useful number this gives you is the form ratio — contact area per unit volume. Compute it and compare like with like:

That thirty-to-fiftyfold spread is exactly why thin walls and small columns cost multiples of what flatwork costs per cubic metre, even though the concrete comes off the same truck at the same price. If you price structural work at flatwork rates because "it's the same concrete," this table is why you lose money.

For labour, published US factors put forming at 0.1667 manhours per SF (6 SF per manhour) and stripping/point-and-patch at 0.1 MH/SF (EWKS/HeavyBid productivity guide). Note that published labour tables generally assume a crew working at around 70% efficiency (Concrete Construction) — your own historicals beat any book rate.

Counts

Pad foundations, bollard bases, pier caps, pockets, drainage boxes, dowels. Count them with a marked symbol on the drawing rather than a tally on a notepad — you'll be interrupted, and a counted mark on the plan survives the interruption.

Annotations — the cheapest insurance on the job

Write your assumptions on the drawing, not in your head:

• "Assumed 150 mm hardcore — confirm."

• "No level information provided — priced on flat subgrade."

• "Excludes cutting/coring by others."

Then issue the marked-up PDF with your quote. Two things happen: the client confirms or corrects your assumption before you're committed, and if it turns out wrong on site you have a dated document showing what you priced. Most disputes on concrete work are scope disputes, and most scope disputes are won on paper.

Step 7: Take off everything that isn't concrete

This is the checklist that separates an estimate from a guess. Every one of these is a real line item, and every one of them gets left out.

Below the slab

• Excavation and cart-away

• Sub-base / hardcore — a minimum of 100 mm / 4 in of compactable material is standard guidance, or at least 75 mm / 3 in of crushed stone sand (NRMCA CIP 29)

• Sand blinding

• Compaction (plant hire and passes)

• Vapour barrier / DPM — minimum 10 mils (0.25 mm), permeance no greater than 0.1 US perms, lapped 150 mm / 6 in at seams and taped around penetrations (NRMCA CIP 29). Those laps plus the perimeter turn-up mean you buy more membrane than slab area. Work it out rather than guessing: on the 420 m² job below, three 150 mm laps across 30 m runs is 13.5 m², and a 150 mm turn-up around 112 m of perimeter is 16.8 m² — 7.2% more membrane than slab.

In the slab

• Mesh or rebar, plus laps

• Chairs and spacers

• Dowels and tie bars at joints

• Isolation joint filler — compressible foam or asphalt-impregnated fibre; note NRMCA's alternative of 50 mm / 2 in of sand over a footing to prevent bond

• Fibres or admixtures if specified

On and after the pour

• Pump or conveyor hire

• Power float / helicopter hire

• Curing compound — a typical ASTM C309 water-based product covers about 200 ft²/gal (4.91 m²/L) (W.R. Meadows datasheet); always use the actual product sheet

• Saw cutting and joint sealing

• Sealers or hardeners

• Concrete testing — ACI 318 requires samples at least once per 150 CY, once per 5,000 SF of slab or wall, and not less than once a day, with a strength test being the average of two 6×12 in or three 4×8 in cylinders (summary of ACI 318 §5.6). Estimators who price testing purely per-150-yards under-count long pours badly, because the once-a-day rule usually governs.

• Protection (frost, rain, traffic)

• Waste removal and final clean

Rebar and mesh: the numbers you need

US bar weights (CRSI Product Catalog) — the bar number is the diameter in eighths of an inch:

Metric bar weights (BS 4449, mass = 0.00785 kg per mm² per metre run):

How to count it: bars per direction = (perpendicular span ÷ spacing) + 1, × bar length, both ways, × mass per unit length, then add laps.

Worked: a 10 m × 12 m slab with H12 at 200 mm centres both ways = 61 bars × 10 m + 51 bars × 12 m = 1,222 m × 0.888 = 1,085 kg, before laps.

A correction worth knowing. The "40 × bar diameter" lap rule is repeated everywhere, and it under-states tension laps in slabs. Published Eurocode 2 guidance gives slab lap lengths of 39Ø–46Ø in good bond conditions and 56Ø–66Ø in poor bond conditions, depending on concrete class (The Concrete Centre, EC2 detailing). For H12 in C25/30 good bond the requirement is 46Ø = 552 mm. The 40d rule gives 480 mm — 13% short of what's needed, meaning you must buy 15% more lap steel than 40d suggests. In poor bond conditions the gap is far wider. Always take laps off the bar schedule where one exists.

UK/IE mesh (BS 4483, standard sheet 4.8 m × 2.4 m = 11.52 m²) (mesh chart):

US welded wire reinforcement (Wire Reinforcement Institute TF 101-R-14) — in 6x6-W2.9xW2.9, the first pair is wire spacing in inches and W-number is wire area × 100:

Mesh lap allowance is jobsite practice rather than a published standard, so do the arithmetic rather than taking a percentage on trust. A 200 mm lap on two edges of a 4.8 × 2.4 m sheet drops effective coverage from 11.52 m² to 4.6 × 2.2 = 10.12 m² — a 14% uplift in sheets. Double the lap to 400 mm and effective coverage falls to 8.80 m², a 31% uplift. Whatever lap you specify, calculate it; don't assume 10%.

Step 8: The worked example — drawing to bid

One job, carried the whole way. Two versions of it, so you can read down whichever column matches your drawings.

• Metric: a 30 m × 15 m yard slab (450 m² gross) less a 6 m × 5 m planted bed, at 100 mm thick, plus 12 no. bollard bases at 450 mm dia × 1.2 m deep.

• Imperial: a 98 ft × 50 ft yard slab (4,900 SF gross) less a 20 ft × 16 ft bed, at 4 in thick, plus 12 no. 18 in dia × 4 ft bases.

Again — these are parallel jobs, not conversions. Read one column.

The quantities

Three things worth pointing at in that table.

Two waste factors, not one. The slab gets 5% — it's a single large, formed, repetitive pour on a screeded subgrade. The bases get 10% — twelve small sporadic elements in hand-dug holes. Rounding up to the nearest half metre (or whole yard) then lands the slab at an effective 6%.

The bases are a short load. 2.5 m³ / 3.5 CY after waste is well under a truck. You will pay a minimum charge and a surcharge on that pour regardless of how little you take. Ask whether it can ride along with the main pour, be done in bagged mix, or be combined with a neighbouring job on the same day.

The formwork includes the bed. You deducted the planted bed from the slab area in Step 3 — but you still have to form its edge. That's 22 m / 72 LF of edge form that lives inside the outline you just deducted.

The estimate

These rates are illustrative. Concrete, aggregate and labour prices vary by region far more than any national average suggests — price from your own current quotes. What matters here is the structure and that no line is missing.

The labour line is an assumed crew loading, not a published rate. It comes from: sub-base prep and compaction 2 days × 3 men; edge forms, DPM and mesh 1.5 days × 3; pour and finish 1 day × 5; saw cut, cure, strip and clean 1 day × 2 — 17.5 man-days. Replace it with your own crew records, which will beat any book rate.

Note what the ready-mix actually is: 26% of the US bid, 23% of the UK one. The concrete everyone argues about on price is a quarter of the number. Labour, groundworks and the finishing trail are the other three-quarters, and they are where estimates go wrong.

Markup is not margin

This trips up more contractors than any formula on this page.

• Markup is a percentage added to cost. Cost × 1.15.

• Margin is a percentage of the sell price. Cost ÷ 0.85.

Apply a 15% markup to $32,812 and you get $37,734 — a 13.0% margin, not 15%. On this one job the gap is $869. Across a year of jobs it's a salary.

To hit a target margin, divide by (1 − margin). For 15%: ÷ 0.85. For 20%: ÷ 0.80. For 25%: ÷ 0.75.

With material prices still moving — Irish ready-mix concrete rose 8.7% in the year to June 2026 while all construction materials rose 3.1% (CSO Wholesale Price Index, June 2026) — the gap between markup and margin is not academic. We've written separately on protecting your margins from rising costs.

What one omission costs

Suppose the saw cutting and curing compound never made it onto the sheet — the two easiest items on this job to forget. That's $1,991, or 5.2% of the bid.

The job's profit at a 15% margin is $5,790. Those two forgotten lines would have taken 34% of it — a third of the profit on a job you priced, won and built correctly, gone before you started, because of two lines on a sheet.

And that assumes you priced everything else right. Set against the CFMA's industry-average 7.7% net margin for specialty trade contractors, the room for error is narrower still.

Sanity-check your number before you send it

Never send a bid you haven't checked a second, independent way. Four fast checks, all of which take under a minute:

1. Volume per unit area. Does the total concrete divide back out to the right depth? 60 CY over 4,580 SF is 1.31 CY per 100 SF, against the 4-inch benchmark of 1.23 plus 6% waste, which is 1.31. It reconciles exactly. In metric: 44.5 m³ over 420 m² is 10.6 m³ per 100 m², against a 100 mm benchmark of 10.0 plus 6%. If yours doesn't reconcile, you've either double-counted a thickening or missed a deduction.

2. Rate per unit area. This job's bid is $8.43 per SF (roughly £58 per m²). Published US benchmarks for a plain concrete slab run $5–$10.50 per SF (HomeGuide, Concrete Network, 2026). Landing at $8.43 for a job that includes saw cuts, a pump, mesh and twelve bases is credible. If you'd come out at $3.50 or $19, something is wrong and you want to know which before the client does.

3. Material as a share of the sell. Ready-mix here is 26% of the bid. If concrete is 60% of your number, you've almost certainly under-priced labour. If it's 10%, check your volume.

4. Form ratio. Contact area per unit volume, compared against the table in Step 6: roughly 0.3 for edge-formed flatwork, 10 for a 200 mm wall, 13 for a small column. If you've priced a wall at a slab's form ratio, the labour is nowhere near enough.

Nine mistakes that cost concrete contractors money

1. Not checking the drawing scale. Everything downstream is wrong and nothing looks wrong.

2. Forgetting the ×2 on formwork. Forms touch two faces of a wall.

3. Missing thickenings and turn-downs. They hide under the slab outline in plan view.

4. Using one waste factor for every pour type. 4% for a repetitive formed pour and 10% for hand-dug footings are both correct — for different jobs.

5. Ignoring short-load and standby fees. On a small pour these can exceed the concrete cost.

6. Pricing rebar laps at 40d without checking the schedule. In C25/30 good bond, 40d is 13% short of the Eurocode requirement, so you need 15% more lap steel than the rule of thumb suggests.

7. Leaving saw cuts, curing and testing off the sheet. Hundreds of linear metres and dozens of gallons, invisible until they're invoiced.

8. Confusing markup with margin. Costs you 2 points on every job you win.

9. Not recovering overhead. If your yard, truck, insurance and estimating time aren't in the number, your "profit" is paying for them.

Where takeoff software actually changes the maths

None of the above requires software. All of it is faster with it, and the gains are concentrated in three places:

• Volume is derived, not calculated. You measure the area once and apply a depth; change the depth and every dependent quantity updates. No re-keying, no stale spreadsheet cells.

• The takeoff is auditable. Grouped, colour-coded measurements mean you can answer "where did 42 cubes come from?" in ten seconds rather than re-measuring.

• The markup travels with the price. The annotated PDF you send with the quote is the same document your crew works from and the same document you'll reach for if scope is disputed.

Worth noting how little of the industry has actually moved: the AGC and Sage's 2026 Construction Hiring and Business Outlook — 951 firms surveyed across 49 states — found only 23% of firms applying AI to estimating, well behind office and administrative use at 45%. Estimating remains one of the least-automated functions in most construction businesses, which is precisely why it's where the easiest gains still are.

Whether it's worth it for you comes down to bid volume — we've laid out the actual break-even in manual takeoff vs. takeoff software, and put numbers on the time cost of scale rulers in the real cost of manual takeoffs. If you're comparing tools, the 2026 takeoff software round-up covers the main options side by side. And if you work across trades, the same method applies — see material takeoffs for roofing contractors for the pitched-roof version.

If you want to see the workflow in this guide run end-to-end on a live set of drawings, the full walkthrough at the top is the fastest way to judge whether it fits how you work. There's a free trial of Assemble Pro if you'd rather try it on your own plans.

Frequently asked questions

What is a concrete takeoff?

A concrete takeoff is the process of measuring every concrete-related quantity from a set of construction drawings — slab and paving areas, footing and wall volumes, formwork contact area, saw cut and joint lengths, and counted items like pad foundations. It produces quantities only. Pricing those quantities is the estimate.

What's the difference between a takeoff and an estimate?

The takeoff produces quantities (m², m³, linear metres, counts). The estimate applies rates to those quantities — material, labour, plant, overhead and margin — to produce a cost and then a bid price. Takeoff answers "how much"; the estimate answers "how much will it cost".

How do you calculate how much concrete you need for a slab?

In metric: area in m² × thickness in metres = volume in m³. In imperial: square feet × thickness in inches ÷ 324 = cubic yards. A 4,580 SF slab at 4 inches is 4,580 × 4 ÷ 324 = 56.5 cubic yards. Add a waste allowance before ordering.

How much extra concrete should I order?

The NRMCA recommends ordering 4% to 10% more than the plan quantity. Use the low end for large, repetitive, well-formed pours with tight thickness control, and the high end for sporadic work, small elements, and footings on uneven or hand-dug subgrade.

Why does a 1/8-inch difference in slab thickness matter?

Because it's 3% of a 4-inch slab. NRMCA calculates that an eighth of an inch of extra thickness on a 4-inch slab creates a 3% shortfall — one cubic yard on a 32-yard order. That single yard usually triggers a second delivery and a short-load fee.

How do I calculate rebar quantities for a slab?

Count bars per direction as (perpendicular span ÷ spacing) + 1, multiply by bar length, do both directions, then multiply total length by the bar's mass per unit length. A #4 bar is 0.668 lb/ft; an H12 bar is 0.888 kg/m. Add laps — and take lap lengths from the bar schedule rather than assuming 40 × diameter, which under-states tension laps in slabs.

How do you measure formwork?

Formwork is measured as contact area — the surface the concrete touches — in m² or SFCA (square feet of contact area). Measure every face in contact: a wall formed on both sides is twice its face area, and a strip footing formed both sides is twice its run.

How far apart should saw cuts be, and how do I quantify them?

Control joints should be spaced 24 to 36 times the slab thickness — about 3 m / 10 ft for a 100 mm / 4 in slab — with a maximum of 4.5 m / 15 ft. Cut to at least a quarter of the slab depth. Quantify in linear metres or linear feet by laying the joint grid over your slab outline.

What's the difference between markup and margin?

Markup is added to cost; margin is a share of the sell price. A 15% markup on a $32,812 cost gives $37,734, which is a 13% margin, not 15%. To hit a target margin, divide cost by (1 − margin): for 15% margin, divide by 0.85.

What profit margin should a concrete contractor aim for?

The CFMA's 2025 benchmarker puts specialty trade contractors at 7.7% net income before tax on average, with gross margin at 22.4%. What you should aim for depends on your overhead structure and risk — but note that with direct costs at 74.2% of revenue and a 7.7% net margin, a 10% quantity error on your direct costs moves 7.4 points of revenue, which is effectively the whole profit.

How long should a concrete takeoff take?

It depends on drawing complexity, but the biggest variable is setup. Contractors who maintain saved group and category templates, and use keyboard shortcuts for pan and zoom, routinely complete takeoffs in a fraction of the time of those starting from a blank sheet each job.

Should I do takeoffs manually or use software?

Manual takeoff with a scale ruler works and is still widely used — JBKnowledge's 2020 Construction Technology Report found 62% of estimating workflows still depended on spreadsheets. The case for software is derived quantities (change a depth, everything updates), auditability, and the marked-up drawing you can issue with your quote. The break-even is usually bid volume: the more jobs you price, the faster it pays back.

Sources

• NRMCA — CIP 31: Ordering Ready Mixed Concrete

• NRMCA — CIP 8: Discrepancies in Yield

• NRMCA — CIP 6: Joints in Concrete Slabs on Grade

• NRMCA — CIP 29: Vapor Retarders Under Slabs on Grade

• CRSI — Product Catalog (bar sizes and weights)

• The Concrete Centre — Eurocode 2 detailing and lap lengths

• Wire Reinforcement Institute — TF 101-R-14

• BS 4483 mesh chart

• CFMA — 2025 Construction Financial Benchmarker

• AGC & Sage — 2026 Construction Hiring and Business Outlook

• HomeGuide — Concrete Prices (Jan 2026)

• Concrete Network — Concrete Prices (Jul 2026)

• RMS Concrete — UK Ready Mix Prices 2026

• Townsend Concrete — Published price list, April 2026

• SJ Civil — Formwork takeoff and SFCA

• Inch Calculator — Concrete Calculator

• The Special Inspector — ACI 318 concrete testing frequency

• Concrete Network — Concrete Calculator (ordering rule of thumb)

• EWKS / HeavyBid — Productivity Factors for Estimating Construction Projects

• Concrete Construction — Estimating Labor Unit Data

• W.R. Meadows — CC-309-1WS curing compound datasheet

• CSO Ireland — Wholesale Price Index, June 2026

• JBKnowledge — 2020 Construction Technology Report

Jonathan Slattery is the CEO of Assemble Pro, takeoff and estimating software built for subcontractors and small builders. Questions on any of the above — jonathan@assemblepro.com.