Units of measure for concrete
Each piece of concrete work has its own unit, and keeping them apart is what makes the estimate checkable. These are the units estimators use and how each is measured.
| Item | Unit | How it's measured |
|---|---|---|
| Footings, walls, slabs | CY | Length × width × depth, converted from cubic feet (27 CF per CY). Measure slabs by area and thickness, thickened edges separately. |
| Formwork | SFCA | Square feet of form in contact with concrete: both faces of walls, both sides of continuous footings, edges of slabs. |
| Reinforcing steel | ton or lb | Bar length by size, plus laps, times the bar's weight per foot (#4 is 0.668 lb/ft). |
| Welded wire mesh | SF or sheets | Slab area plus side laps, divided by the sheet size. |
| Place and finish | SF | Finished area by finish type (steel trowel, broom, polished). |
| Vapor retarder, joints, curing | SF / LF | Slab area for retarder and curing; saw-cut joints by linear foot. |
How estimators take off concrete
- List the elements from the structural drawings. Footings, grade beams, piers, walls, slabs on grade, elevated slabs and site concrete each get their own line, because each forms, reinforces and finishes differently.
- Measure volume for each element. Length × width × depth for every area, with counts for repeated pads. Keep thickened slab edges and depressions as separate items so they aren't lost in an average thickness.
- Add waste and round to what the plant sells. Add 5% for over-excavation, uneven subgrade and spillage (more on rough footings), then round each pour up to the plant's minimum increment.
- Measure forms and rebar separately. Forms by contact area; rebar by size and length with 10% added for laps in 20 ft bars, then converted to weight. Mesh gets 10% for laps.
- Price labor from crew production. Divide each quantity by a crew-day rate (slab placing, forming, rebar) to get crew-days, then multiply by the crew's burdened daily cost.
- Add pumps, testing and protection. Pump or crane time, finishing equipment, curing, hot or cold weather protection and testing are line items, not something to bury in the yard price.
Waste factors and order quantities
Waste covers cut-offs, breakage, laps and spillage, and it's added to the net quantity before rounding up to what the supplier sells. Figures marked as tool defaults are the same ones the Trade Takeoff Worksheets start with, and you can edit them there.
| Item | Factor | Notes |
|---|---|---|
| Concrete | 5% | Tool default. Raise it for footings poured against earth or uneven subgrade. |
| Rebar laps | 10% | Tool default, in 20 ft stock lengths. |
| Mesh laps | 10% | Tool default, 160 SF sheets (8 × 20). |
Crew production rates
Labor is quantity divided by production. These rates are per 8-hour crew-day for commercial work, from the same library as the crew-day production estimator: typical mid-range planning values with a low-to-high range, not a promise of output. Crew skill, layout, access and weather move them, and your own crews' records beat any library.
| Activity | Crew | Low | Typical | High | Labor |
|---|---|---|---|---|---|
| Place and finish slab on grade, 4 to 6 in | 2 finishers, 4 laborers | 3,000 | 4,000 SF | 5,500 | 1.2 hrs per 100 SF |
| Form continuous footings | 2 carpenters, 1 laborer | 250 | 320 SFCA | 400 | 7.5 hrs per 100 SFCA |
| Form foundation walls, gang forms | 3 carpenters, 1 laborer | 350 | 480 SFCA | 650 | 6.7 hrs per 100 SFCA |
| Place reinforcing steel | 3 ironworkers | 1.5 | 2 ton | 3 | 12 hrs per ton |
- Place and finish slab on grade, 4 to 6 in 3,000 to 5,500 SF, typical 4,000
- Form continuous footings 250 to 400 SFCA, typical 320
- Form foundation walls, gang forms 350 to 650 SFCA, typical 480
- Place reinforcing steel 1.5 to 3 ton, typical 2
Worked example: a 12,000 SF slab on grade
The activity is place and finish slab on grade, 4 to 6 in, with a crew of 2 finishers, 4 laborers at the typical rate of 4,000 SF per crew-day:
- Crew-days: 12,000 SF ÷ 4,000 = 3 crew-days.
- Labor hours: 3 crew-days × 6 workers × 8 hours = 144 hours.
- Range: 2.2 crew-days at the high rate to 4 at the low rate, a spread of 1.8 crew-days on the same quantity.
- Equipment: Power trowel, about 6 equipment-days.
Multiply the labor hours by your burdened hourly cost to price the labor. The spread between the low and high rate is why production is the assumption to check first on a concrete bid: the same takeoff can carry very different labor. Run your own quantities in the crew-day production estimator, and get the burdened rate from the labor burden calculator.
What drives the cost
- Placement method. Chute, buggy, pump or crane and bucket. Pump time and minimum charges often decide whether a small pour makes money.
- Form reuse. Gang forms that cycle many times are far cheaper per SFCA than one-off forms at odd shapes, columns and blockouts.
- Finish and flatness. Tighter FF/FL numbers, polished or hardened finishes and joint layouts add finishing labor and equipment time.
- Weather. Hot and cold weather concrete needs admixtures, blankets, heat or night pours, all priced separately.
- Rebar density. Congested steel slows placing and vibration; heavy mats also raise ironworker hours per ton.
Common exclusions and clarifications
A concrete price is only as good as the scope it describes. These exclusions come from our scope library for concrete (CSI 03 30 00); list the ones that apply so the GC levels your number fairly.
- Excavation, backfill, compaction and fine grading below slabs.
- Testing, special inspections and survey layout.
- Hot and cold weather protection.
- Pumping over the quantity stated.
- Floor flatness beyond FF25/FL20.
- Polished, stained or sealed finishes unless listed as included.
Clarifications that often go with them:
- Pricing assumes subgrade is provided compacted and within 0.1 ft of grade by others.
- Pour sizes and sequence per the approved pour plan; additional mobilizations are extra.
Pick, edit and export these in the scope inclusions and exclusions library, or load them straight into a proposal with the bid proposal builder.
Free tools for concrete estimating
- Trade takeoff worksheets: measure concrete areas and get order quantities with the same waste factors, then download an Excel takeoff.
- Crew-day production estimator: turn concrete quantities into crew-days, duration and labor hours with the rates on this page.
- Labor burden calculator: find the true cost of a crew hour, with taxes, insurance and benefits.
- Scope inclusions and exclusions library: pick proposal-ready concrete exclusions and clarifications.
- Bid proposal builder: send a branded concrete proposal with the scope language loaded.
- Equipment own vs rent calculator: compare the hourly cost of owning a machine with renting it.