Concrete Takeoff: How to Calculate Cubic Yards from a Plan
How to do a concrete takeoff: turn plan dimensions into cubic yards with one formula, with worked examples for slabs, footings, walls and piers, plus waste.
June 12, 2026 · 7 min read
Concrete is sold and ordered by the cubic yard, but plans give you dimensions in feet and inches. A concrete takeoff is the process of turning those plan dimensions into cubic yards you can order and price. The math is simple once you see it; the care is in measuring the right areas and not forgetting the waste.
The one formula to remember
Cubic yards cubic yards = (area in square feet × thickness in feet) ÷ 27. The 27 converts cubic feet to cubic yards, because 1 cubic yard = 3 ft × 3 ft × 3 ft = 27 cubic feet. Always convert thickness from inches to feet first: inches ÷ 12.
Start freeThat single formula covers slabs, footings, walls, piers and columns. Everything else is just measuring the right area and thickness off the plan.
Step 1: Convert thickness to feet
Plans give slab and footing thickness in inches. Divide by 12 to get feet. A 4-inch slab is 4 ÷ 12 = 0.333 ft; a 6-inch slab is 6 ÷ 12 = 0.5 ft; an 8-inch wall is 8 ÷ 12 = 0.667 ft. Do this first and the rest is multiplication.
Step 2: Measure the area
For a slab, measure the footprint in square feet. A rectangular 30 ft × 40 ft slab is 1,200 SF. For an irregular shape, break it into rectangles and triangles, or trace the outline in takeoff software, which computes the area from the geometry. Use the calibrated plan scale, never the printed nominal scale on a reduced sheet.
Step 3: Calculate the volume
Multiply area × thickness ÷ 27:
- Slab, 4 inch: 1,200 SF × 0.333 ÷ 27 =
14.8 CY. - Slab, 6 inch: 1,200 SF × 0.5 ÷ 27 =
22.2 CY.
Footings and walls use the same formula
A continuous footing is just a long, narrow slab. Measure its length and multiply by width and depth. A footing 120 LF long, 24 inches (2 ft) wide and 12 inches (1 ft) deep is 120 × 2 × 1 ÷ 27 = 8.9 CY. A wall is the same idea stood on edge: length × height × thickness ÷ 27. A wall 80 LF long, 8 ft tall and 8 inches (0.667 ft) thick is 80 × 8 × 0.667 ÷ 27 = 15.8 CY.
Columns and piers
For a rectangular column, volume = width × depth × height ÷ 27. For a round pier, use the circle area: π × radius² × height ÷ 27. A 12-inch (1 ft) diameter pier 4 ft tall has a 0.5 ft radius: 3.1416 × 0.5² × 4 ÷ 27 = 0.12 CY each. Multiply by the count of piers from your takeoff.
Step 4: Add waste
Always order more than the calculated volume. Subgrade is never perfectly flat, forms flex, and some concrete is lost to spillage and the chute. A common allowance is 5–10%, more for a slab on rough subgrade, less for formed work. On the 14.8 CY slab above, a 10% allowance brings the order to about 16.3 CY.
Round to the delivered yard
Ready-mix plants deliver in fixed increments, typically quarter- or half-yard steps, and most charge a short-load fee below a minimum. Round your final number up to the next increment the plant offers rather than ordering an exact decimal, running short mid-pour costs far more than a little extra mud.
Don't forget the count items A concrete takeoff is more than volume. Rebar and mesh are measured by linear feet or area, anchor bolts and dowels are counted, and forms are measured by the square foot of contact area. The cubic yards price the mud; these price the rest of the assembly.
Start freeDoing it on screen
Takeoff software removes the arithmetic errors: calibrate the scale once, trace the slab or footing, set the thickness, and the cubic yards are computed for you, including the irregular shapes that are painful by hand. For a quick one-off, the free concrete calculator does the volume math without an account; for a full project, the concrete takeoff guide covers slabs, footings, walls and rebar together.
JobPlumb computes concrete volume from the geometry you trace and rolls it straight into a priced estimate. Start a free project and measure your next pour in the browser.