Concrete Estimate Template: Volume, Pump and Finishing Lines With AI

Multiply length by width by thickness in one unit, add any thickened edge, then add waste (a common rule of thumb is 5 to 10 per cent) and round up to the ordering step. Price the pump, placing, finishing and curing as separate lines. A 6 m by 4 m slab with a thickened edge comes to 3.5 m³.

The sum itself is easy. Estimates go wrong on units, on lines nobody thought of (short-load fees, wash-out, saw-cutting) and on rates copied from the last job. So the sheet below keeps the arithmetic in formulas, and AI does the jobs it is good at here: drafting the layout, turning site notes into lines and auditing the finished estimate for gaps. Asking a chat assistant to work out the volume on its own is the one use I would avoid.

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The slab we are pricing, and why every rate here is a placeholder

Say a two-crew groundworks firm has been asked to price a concrete base for a garden workshop. The brief is short:

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• Slab 6.0 m by 4.0 m, 100 mm thick, with a thickened edge 300 mm wide and 150 mm deeper than the slab, on 100 mm of compacted sub-base.
• Access is a side passage about 22 m from the road, so a line pump is on the table.
• Standard mix; the supplier's minimum load is 4 m³ and it orders in 0.5 m³ steps.
• Broom finish, saw-cut joints the same day, within hours of finishing, and two coats of curing compound.

Every rate and hour in this tutorial is a round placeholder picked to keep the arithmetic readable; treat none of them as a market rate. Swap each for your supplier's current price or your own job records, and keep a "Source of rate" column so you can see which cells are real. Metric units lead because the arithmetic is cleaner; cubic yards appear where they help.

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Volume first: slab, thickened edge, waste and the ordering step

Work in metres throughout. A thickness of 100 mm is 0.100 m, and typing 100 into a cell that expects metres is the classic way to price 2,400 m³ of concrete for a patio. The slab is 6.0 × 4.0 × 0.100 = 2.40 m³. The thickened edge is a strip round the perimeter: 20.0 m × 0.30 m × 0.15 m = 0.90 m³. Measuring along the outside edge counts the four corner squares twice, about 0.05 m³ extra: small, on the safe side, and worth knowing if an engineer checks your figure. Leaving the edge out is an easy way to run short mid-pour, because a slab-only number looks perfectly plausible.

I used 6 per cent for waste. Concrete Network's ordering advice is never to order the exact amount: a 20 yd³ order that finishes with 1 yd³ left over is, in its words, a good order, and that margin is 5 per cent. Most estimators carry somewhere between 5 and 10 per cent, but the right figure for you is whatever your last ten pours actually over-ordered. Rough ground, hand-dug trenches and long barrow runs push it up; a tidy formed slab on a levelled sub-base pushes it down.

Imperial readers can run the same sum: length in feet × width in feet × thickness in inches ÷ 12 gives cubic feet, and dividing by 27 gives cubic yards. A 20 ft by 13 ft slab at 4 in is 20 × 13 × (4 ÷ 12) = 86.7 ft³, or 3.2 yd³. For reference, 3.3 m³ is about 4.3 yd³ and 3.5 m³ is about 4.6 yd³.

Two checks that take ten seconds

• Volume against area. Net volume divided by slab area should land near the slab thickness. Here 3.30 ÷ 24 = 0.1375 m, a little above 0.100 m because of the edge. An answer of 10 m or 0.01 m means a unit slip.
• Order against the minimum load. At 3.5 m³ this order is under the supplier's 4 m³ minimum, so a short-load fee applies. Ordering the full 4.0 m³ would add 0.5 m³ of concrete, fibre and pumped volume (0.5 × ($160 + $9 + $6) = $87.50) against a $150 fee, so the bigger order is cheaper on paper, provided the spare half cubic metre has somewhere useful to go. The estimate carries the fee and the alternative is raised on the pour-day call.

Set up the sheet so the formulas do the arithmetic

The layout has four blocks. Inputs sit in a single column so nothing is typed into a formula, the volume block reads from the inputs, the estimate lines carry their own quantities and rates, and the totals sit at the bottom.

Slab m³             C12  =B2*B3*B4
Edge m³             C13  =2*(B2+B3)*B5*B6
Net m³              C14  =C12+C13
Order m³            C15  =CEILING(C14*(1+B7),B8)
Short-load flag     C16  =IF(C15<B9,"Short load: check fee","")
Line total          F20  =C20*E20          (copy down)
Direct cost         F40  =SUM(F20:F39)
Contingency         F41  =F40*B10
Cost                F42  =F40+F41
Overhead and profit F43  =F42*B11
Price               F44  =F42+F43

If you would rather not type those, an assistant can draft the layout. The prompt below says what to build and, just as important, what not to invent.

You are helping a small concrete contractor build a reusable estimate sheet in Excel.
Job type: residential slab on grade, placed by line pump or by barrow, broom finish.
Build: (1) an inputs block: length, width and thickness in metres, thickened edge
width and extra depth, waste percentage, supplier ordering step, supplier minimum
load, contingency %, overhead-and-profit %; (2) a volume block using formulas that
refer to the inputs, never typed-in numbers; (3) estimate lines grouped as Prep,
Concrete, Pump, Labour and Finish with columns Code, Description, Qty, Unit, Rate,
Total, Source of rate, Checked; (4) totals.
Return the layout as a table and write every formula in Excel syntax.
Do not invent any rates. Leave every Rate cell empty.

Check the first answer for two common slips: a waste factor typed into the formula (1.06) instead of pointing at the waste cell, and the pump wash-out filed under labour, which hides it when you change crews. If you work in Excel, the Copilot in Excel tutorial covers writing formulas straight into the workbook. The Checked column earns its place: a line only gets a Y once its rate matches a supplier quote or your own job record.

Pump lines: what the quote must state, and when a barrow wins

A line pump (hoses run from a truck or trailer unit) is a common choice for small slabs, long runs from the road and awkward access. Boom pumps, with an articulated arm, are for reach and big volumes. For a 3.5 m³ pour behind a house you are almost certainly pricing a line pump, and the estimate should show each part of its charge separately, because they behave differently when the job changes:

• Call-out and included time. A fixed charge that covers set-up and a stated number of hours (2 in this example).
• Volume or extra-time charge. Per cubic metre pumped, or per hour beyond the included time.
• Hose. How much is included and the rate per extra metre. A 22 m run from the road is the sort of detail that decides whether the quote holds.
• Waiting and cancellation. What the pump company charges if the truck is late, the site is not ready or you cancel, and the cut-off hour.
• Wash-out. The charge, and where the waste is allowed to go. A contained wash-out area is a cost line of its own.

With the placeholder rates the pump lines come to $380 + (3.5 × $6) + $60 = $461. Now the barrow comparison. Suppose the crew reckons barrowing the same 3.5 m³ down the passage needs two extra people for two hours: 4 labour-hours × $40 = $160. On paper the barrow saves $301. That is the crew's estimate, not the assistant's, and it only holds if the pour stays continuous. If the truck waits, or the concrete is still being moved when it starts to set, the saving disappears and the surface suffers. Ask the crew, then write the decision next to the line so the client's quote and the site plan agree.

Access leaves its fingerprints on other lines too. A passage too narrow for a mini-digger turns A1 and A2 into hand digging, so those rates change. A lorry that cannot reach the plot may need ground protection boards, which is a line of its own, and a long barrow run adds labour to D1. Record the access facts on the site-visit sheet (passage width, surface, distance from the road, overhead obstructions), because they move several lines at once.

If your jobs vary a lot in pump access, keep a second set of pump lines hidden in the sheet and switch between them. That also makes it easy to see what a customer who asks for "just a barrow" is really saving.

Finishing lines: hours, joints and curing from your own jobs

Finishing labour is where placeholder numbers do the most damage, because it varies by crew, mix and weather. Record actual hours on every slab you pour (place and screed, float and edge, joint, broom, cure) and divide by area. The example above uses 12 hours to place and screed and 6 to float, edge, joint and broom: 18 labour-hours for 24 m², or 0.75 per m², which is high for an open slab but plausible for a small one with a thickened edge and a 22 m run. Your own history is the benchmark, not mine.

Three details change the lines:

• Timing is set by the concrete, not the clock. Final finishing waits until bleed water has gone and a footprint leaves an indent of about 3 to 6 mm (1/8 to 1/4 in). Industry guidance gives a rule of thumb that a 10 °C (20 °F) drop in concrete temperature roughly doubles setting time, so a cold day means later finishing and longer hours. Add the hours on cold days, or carry a weather contingency line.
• Joints. The NRMCA guidance on joints caps contraction joint spacing at 24 to 36 times the slab thickness. At 100 mm that is 2.4 to 3.6 m. Panels should be roughly square, with length no more than about 1.5 times the width. For 6 m by 4 m, one cut across at 3 m and one along at 2 m gives four 3 m by 2 m panels and 10 m of saw-cut, which is the quantity in line D3. The same guidance gives the timing: conventional saw-cuts within 4 to 12 hours of finishing, early-entry dry-cut saws 1 to 4 hours after, and a groove at least a quarter of the slab thickness deep (not less than 25 mm). Finish at 13:00 and the conventional window closes around 01:00, so a site note that says "saw-cut next day" is a timing error to fix before it reaches the crew. The cut is a scheduled visit, not an afterthought.
• Curing. Guidance describes curing as typically 3 to 7 days, starting straight after finishing; a liquid curing compound goes on once the water sheen has disappeared, and two coats applied at right angles is described as desirable. Price the compound, the sheeting if you use it, and the labour to apply and check it. Plastic sheeting can mottle a surface where appearance matters, so say which method you are pricing.

The finish you promise also moves the lines. A broom finish is the usual choice outdoors because it gives grip when wet; a steel-trowelled finish is smoother and slippery when wet, and trowelling air-entrained concrete needs care. Decorative finishes such as exposed aggregate or stamping call for special procedures, so price them as their own lines, not as a surcharge on the broom finish.

The estimate in full, line by line

Here is the finished sheet for the workshop base. The quantities come from the volume block and the job brief; the rates are placeholders.

By group, and rounded to the nearest per cent, the direct cost splits into prep $1,179.50 (35 per cent), concrete $741.50 (22), pump $461.00 (14), labour $898.00 (27) and finish materials $105.00 (3). The shape is what you compare against past jobs, not the dollar figure. If the pump share doubles on the next job, that tells you the access has changed. If labour per m² drifts up over five slabs, your hours column is out of date.

The soft patch by the fence is deliberately not in the total. It goes into the quote as a provisional rate per cubic metre with a clause about unforeseen ground, which the concrete quote template tutorial covers. The difference between an estimate and a quote, and what each commits you to, is set out in quote versus estimate for trades.

Audit it with AI: the prompt, the flags and what to reject

Before the estimate leaves the office, paste the draft into an assistant and ask it to look for what is missing, not to rewrite anything. The first draft of this estimate did not have lines A2, B2, E1 and E2.

Act as a second estimator reviewing a concrete slab estimate.
Job: 6 m x 4 m slab, 100 mm thick, thickened edge 300 mm wide x 150 mm deeper,
line pump, 22 m from the road, supplier minimum load 4 m3, orders in 0.5 m3 steps.
Below is my draft estimate (code, line, qty, unit, rate, total).
List only: (a) lines a job like this normally needs that are missing, (b) quantities
that do not match the dimensions, (c) any unit that looks wrong.
For each flag give the reason in one sentence and say how sure you are.
Do not change my rates and do not suggest a price.

An illustrative reply, and what I would do with each flag:

1. No excavation for the 20 m thickened edge, about 0.9 m³ more spoil. Right. Added as A2, $49.50.
2. Order is 3.5 m³ against a 4 m³ minimum: is there a short-load fee? Right, and it needed a phone call to confirm the amount. Added as B2, $150.
3. Curing labour is priced but there is no curing compound or sheeting material. Right. Added as E1, $60.
4. No wash-out area or waste disposal for pump and barrow residue. Right. Added as E2, $45.
5. Pump call-out includes 2 hours but placing labour is 4 hours. Rejected. The labour hours are people on site; the pump is only needed while concrete is placed, about an hour.
6. Traffic management not priced. Rejected. A private rear garden needs none.

The four additions are $304.50 of direct cost. After contingency and overhead and profit, that moves the price from $3,881.44 to $4,265.10, an increase of $383.66, just under 10 per cent. Underpricing by that much on every job is how a firm with a full order book still struggles for cash. Run the audit twice, once in each of two different assistants, and read both lists, because they can miss different things. Nothing an assistant suggests goes in without a person deciding it applies.

The realistic failure to expect

Ask an assistant for the volume with no working shown and it may return 2.4 m³, the slab alone. That looks right. You order 2.5 m³, the truck runs dry about 3 m from the end of the pour, and you phone for a second delivery of 0.9 m³ that arrives after the first load has started to set. The result is a short-load fee and a visible joint line across the slab. The cure is simple: always ask for the volume by component (slab, edge, anything else) and compare each part with the sheet.

From messy site notes to estimate lines

Site notes arrive as voice memos and half-sentences. An assistant can turn them into lines, provided it is told to ask rather than guess. This prompt forces that:

Turn these site notes into estimate lines, one line per cost. Use only these units:
m3, m2, lm, h, item. If a quantity or unit is missing, write ASK instead of guessing.
Do not add prices.
Notes: Workshop base at the back, 6 by 4, 100 thick, thick edge all round. Side
passage only, about 22 m from the road, so pump. Two coats of curing compound.
Saw-cut same day. Soft ground by the fence.

A sample reply: excavate working area (ASK: depth and spoil removal not given); sub-base (ASK: thickness not given); slab 6 × 4 × 100 mm, 24 m² and 2.4 m³; thickened edge (ASK: width and depth not given); line pump with 22 m hose run (ASK: hours on site); curing compound, two coats, 24 m² (two passes); saw-cut joints (ASK: layout not given); soft ground by the fence, provisional sum (ASK: extent not given). Six of the eight lines carry a question. That is the value: each ASK becomes a question for the client or the site visit instead of a guess buried in the price.

The same trick improves how the lines read to the client. Compare a draft line, Pump, with the rewritten Line pump, 22 m hose run from the road via the side passage; call-out includes the first 2 hours on site; wash-out included. The second version tells the client what they are paying for and gives you something to point at if the access turns out to be different on the day.

Four other slabs on the same sheet

The same inputs handle most small jobs. These quick sums use 6 per cent waste and a 0.5 m³ step, except the footing, where concrete poured into dug trenches usually needs a bigger allowance, so it uses 10 per cent. The supplier's minimum load is 4 m³ as before.

Two of the four jobs hit a short-load fee, which is why that flag sits next to the order volume. For a cut-and-fill style quantity such as a large excavation, the volume maths is different enough to deserve its own tutorial: earthworks estimating with AI covers where assistants help and where they do not.

Keep the sheet honest after each pour

An estimate template only improves if the actuals flow back. After every pour, add one row to a log: cubic metres ordered, cubic metres actually placed, hours by group, pump invoice and anything that surprised you. After five or six jobs, give the log to an assistant with a narrow question:

Here are my last six slab jobs: ordered m3, placed m3, labour hours by group, pump
invoice total, area in m2. Calculate for each job: over-order percentage and labour
hours per m2. Then give me the average and the range for each. Do not recommend
prices. Flag any job that looks like an outlier and say why.

Use the average over-order to reset the waste cell and the labour hours per m² to sanity-check the hours column. Nothing here replaces judgement about a particular site. It stops the sheet drifting away from what your crews actually do. When you are ready to turn an estimate into a priced bid, how to bid concrete jobs picks up from here, and the pour-day planning in the concrete pour schedule tutorial uses the same order volume and pump window.

Questions about pricing a slab

How much extra concrete should I order for waste?

A common rule of thumb is about 5 to 10 per cent over the calculated volume. Use your own history rather than the rule: compare cubic metres ordered with cubic metres poured on your last ten slabs, then set the waste cell to that average plus a small margin. Tight formed slabs sit near the bottom of the range; trench pours and long barrow runs sit near the top.

Can ChatGPT or Copilot work out the cubic metres for me?

It can, and it can also slip: dropped edge beams, millimetres treated as metres and rounding in the wrong direction are the usual faults. Keep the volume in sheet formulas, then ask the assistant to recompute from the same inputs and show its working for each component. If its answer differs from the sheet by more than one ordering step, find the difference before you order.

Should the pump be a flat fee or priced per cubic metre?

Price whatever the pump company's quote says, line by line. Ask what the call-out includes, the minimum hire time, any charge per cubic metre or per hour beyond it, how much hose is included, waiting time, cancellation terms and wash-out. Put each in its own estimate line so you can see which ones change when the volume or the access changes.

Does the estimate change for cold or hot weather?

Yes, mainly in labour and protection lines. Industry guidance notes that concrete sets roughly twice as slowly for every 10 °C (20 °F) drop in its temperature, so finishing starts later and crews stay longer. Hot, dry or windy days add windbreaks, fog spray or evaporation retarder. Add a weather contingency line rather than burying these costs in labour.

Further reads

• Concrete Contract Template: Payment, Cracking and Delay Terms With AI — What to bind in writing once the client accepts the price.
• Construction Estimating With AI: Turn Supplier Quotes Into a Rate Sheet — Keep the rates in this sheet current from supplier quotes.
• AI for Concrete Contractors: Estimating, Pour Scheduling and Weather Calls — How AI fits across a concrete firm's whole week.
• Should You Charge for Estimates? A Decision Rule for Small Trades — Decide when a detailed estimate like this should be paid for.
• ChatGPT for Construction Estimating: Check a Quote, Do Not Write It — Use ChatGPT to check a quote rather than write it.
• Demolition Estimate Template: Scope, Waste and Disposal Lines With AI — A demolition estimate template for a rear extension: scope, asbestos and services exclusions, tonnes by waste stream, and skip and disposal lines.
• Groundworks Quote Template: Dig, Drain and Base Lines Written With AI — A filled-in groundworks quote for a base and drain: the columns, the quantity sums, the provisional items and the prompt that turns site notes into lines.
• Siding Estimate Template: Squares, Trim and Waste Lines Written With AI — A siding estimate laid out line by line, with the squares, trim and waste sums worked from wall measurements and a ChatGPT pass for missing items.
• AI Tools and AI Development: The Complete 2026 Guide — the AI hub, including every tutorial in the AI-for-business series.

Sources: NRMCA Concrete in Practice sheets on cracking and joints (CIP 4 and 6), finishing flatwork (CIP 14), curing (CIP 11) and cold-weather concreting (CIP 27); Concrete Network's calculator FAQ on ordering a margin of safety; reference descriptions of line and boom concrete pumps.