What quantities does a concrete slab job need?

It depends on the measurements, so this page asks for yours. At the size it opens on — Slab length 6 m · Slab width 4 m · Slab thickness 0.1 m — the lines come to: Concrete, 2.52–2.76 m³; Rebar, 11 x 12 m sticks; Concrete Formwork, 9–10 x 2.4 m boards. In imperial units — Slab length 19.5 ft · Slab width 13 ft · Slab thickness 4 in — they come to: Concrete, 3.29–3.6 cubic yards; Rebar, 21 x 20 ft sticks; Concrete Formwork, 9–10 x 8 ft boards.

Which line on a concrete slab quote varies the most?

The Concrete Formwork: 9–10 x 2.4 m boards for a job measured Slab length 6 m · Slab width 4 m · Slab thickness 0.1 m, depending on the cutting allowance allowed, from 5% to 15%.

What does a concrete slab quote often leave out?

The reading names every line of the job that nothing on the quote reads as — any of the 3 lines the takeoff measures. The takeoff also lists 5 things it does not measure, shown under the reading, and each is worth asking about: a scope missing from a quote tends to become a cost after work has started.

Can I paste the quote exactly as it came?

Yes — from an email, a PDF or a spreadsheet, one item to a line. Amounts of money are taken out before anything is read, headings and totals are skipped, and each line is shown with what it was read as, so a misreading is one correction. Quantities in the other unit system are converted and the conversion is shown; a count of boxes is never compared with a count of tiles.

Does this check the price as well?

No. It reads quantities, never prices, and this site publishes none: an installed price moves with the market, the season, the access and the specification, so a figure for what the work ought to cost would give you confidence in a number nobody can defend. A quantity against your own measurements is checkable, and every figure here links to the calculator that produced it.

Quote check

Check a concrete slab quote

Paste the quote you were given and enter your measurements. Every line is read against the job: what the quote leaves out, what it adds, which quantities sit outside the computed range, and what to ask. Quantities only — never prices.

3Lines the job needs
3Measurements
QuestionsNever a verdict

Timber-framed house under construction with ladders, sawhorses and lumber

How the quote is read

Each line of a concrete slab quote is matched to the line of the job it names, or marked as something the Concrete slab takeoff does not measure — labour, removal, hire, fees, or anything else.

The job’s own figures come from 3 measurements — slab length, slab width, slab thickness — run through the same calculators as the takeoff, so the two give the same figure for the same job.

Reading a concrete slab quote

Concrete is quoted by the volume delivered, and that volume should already carry an over-order for spillage and an uneven sub-base; worth asking whether it does, or whether a short load would be charged as extra.

Reinforcement is often described by mesh or bar size rather than by a count, and a quote that names neither leaves the slab's one structural line open. Formwork may be hired or built, and the two are priced quite differently.

Three steps

Give your measurements. The page opens on a typical job so it has something to show.
Paste the quote's lines as they came, or add them one at a time. Leave the prices in — they are taken out, never read.
Read the report: what is left out, what is added, what sits outside the range, and one list of questions to send.

Your quote

The concrete slab quote you were given

Paste from an email, or open or drop a PDF, Excel, CSV or text file, or a photo of the quote. Amounts of money are taken out before anything is read — this page compares quantities, never prices.

Nothing you paste or open leaves this device.

or one the job needs:

The reading

What the quote says, against the job

Concrete slab · Slab length 19.5 ft · Slab width 13 ft · Slab thickness 4 inSlab length 6 m · Slab width 4 m · Slab thickness 0.1 m

What it leaves out
Every line the job needs that nothing on the quote reads as, with the quantity your measurements produce.
What it adds
Lines this job's takeoff does not measure — labour, removal, hire, fees, anything else — each named for what it is.
What sits outside the range
Quantities above or below the computed range, by how much, in the quote's unit or converted and shown.
What to ask
One list of questions, in the quote's order, ready to copy and send. Questions, never a verdict.

Paste the quote above, or add its lines one at a time. The reading appears here as each line is read.

Outside what this takeoff measures

Nothing in the reading measures these. Whether the quote covers each is worth asking in its own right: a scope missing from a quote tends to become a cost after work has started. Why each is left out is on the takeoff.

Any structural design
Excavation, spoil removal and the sub-base
Damp-proof membrane, radon barrier and under-slab insulation
Chairs, tying wire and edge thickenings
The pour itself

The reference

Every line the reading looks for

For Slab length 19.5 ft · Slab width 13 ft · Slab thickness 4 inSlab length 6 m · Slab width 4 m · Slab thickness 0.1 m. Each is the calculator linked under it, run with those measurements; a range is that calculator at both ends of one choice, not a margin for error.

Concrete
3.29–3.6 cubic yards
3.29 at 5% waste factor, 3.6 at 15%.
Open the Concrete Calculator
Rebar
21 x 20 ft sticks
One figure, with the lap-splice allowance the material needs already inside it at 15%.
Open the Rebar Calculator
Concrete Formwork
9–10 x 8 ft boards
9 at 5% cutting allowance, 10 at 15%.
Open the Concrete Formwork Calculator

Concrete
2.52–2.76 m³
2.52 at 5% waste factor, 2.76 at 15%.
Open the Concrete Calculator
Rebar
11 x 12 m sticks
One figure, with the lap-splice allowance the material needs already inside it at 15%.
Open the Rebar Calculator
Concrete Formwork
9–10 x 2.4 m boards
9 at 5% cutting allowance, 10 at 15%.
Open the Concrete Formwork Calculator

How the ranges are taken

Where the choice is cutting waste, the ends are the site’s own allowances: 5%, the tight buffer of a crew with a planned set-out, and 15%, the wider one a first-timer orders. Where the calculator decides between patterns or materials, the ends are the options it offers. Where it adds nothing for loss, the range runs from the net quantity to 15% over it.

A minimum — the fewest hangers a spacing allows, the least airflow a room needs — has no upper end. A single figure carries an allowance the material itself needs, such as a lap, and names it.

What a reading like this cannot see

It does not know your prices, your market, or what the work ought to cost.
It does not know the building — the access, the condition of what is there, or what has to happen first.
It cannot check a lump sum, because there is no quantity in one.
A line it reads as missing may be priced under another name. A quantity outside the range is not evidence of anything. Each is a reason to ask a question.
Two quotes are not comparable until their scopes are.
It is not advice, and it is no substitute for a second quote.

The full takeoff

Every quantity for this job, with its working

The Concrete slab takeoff runs the same calculators on the same measurements and shows what sits under each line here.

Open the takeoff Every quote check

Base, allowance, order
Each line's quantity before and after its allowance, and what to buy.
Every allowance editable
Change a waste figure and the order follows, with its source named.
Into a project
Add the whole job to a workspace with your own prices.

Frequently asked questions

What quantities does a concrete slab job need?: It depends on the measurements, so this page asks for yours. At the size it opens on — Slab length 6 m · Slab width 4 m · Slab thickness 0.1 m — the lines come to: Concrete, 2.52–2.76 m³; Rebar, 11 x 12 m sticks; Concrete Formwork, 9–10 x 2.4 m boards. In imperial units — Slab length 19.5 ft · Slab width 13 ft · Slab thickness 4 in — they come to: Concrete, 3.29–3.6 cubic yards; Rebar, 21 x 20 ft sticks; Concrete Formwork, 9–10 x 8 ft boards.
Which line on a concrete slab quote varies the most?: The Concrete Formwork: 9–10 x 2.4 m boards for a job measured Slab length 6 m · Slab width 4 m · Slab thickness 0.1 m, depending on the cutting allowance allowed, from 5% to 15%.
What does a concrete slab quote often leave out?: The reading names every line of the job that nothing on the quote reads as — any of the 3 lines the takeoff measures. The takeoff also lists 5 things it does not measure, shown under the reading, and each is worth asking about: a scope missing from a quote tends to become a cost after work has started.
Can I paste the quote exactly as it came?: Yes — from an email, a PDF or a spreadsheet, one item to a line. Amounts of money are taken out before anything is read, headings and totals are skipped, and each line is shown with what it was read as, so a misreading is one correction. Quantities in the other unit system are converted and the conversion is shown; a count of boxes is never compared with a count of tiles.
Does this check the price as well?: No. It reads quantities, never prices, and this site publishes none: an installed price moves with the market, the season, the access and the specification, so a figure for what the work ought to cost would give you confidence in a number nobody can defend. A quantity against your own measurements is checkable, and every figure here links to the calculator that produced it.