MATERIAL AND PROJECT ESTIMATES
Estimate cubic yards of concrete from slab length, width, depth, and a waste allowance you choose.
Your result
Enter your values and select Calculate. Your result stays on this device.
Cubic yards = length ft × width ft × (depth in ÷ 12) ÷ 27, then the entered allowance is added.
A rectangular slab with uniform depth; grade variation, footings, beams, forms, and supplier minimums are not modeled.
This concrete calculator converts a simple rectangular slab from feet and inches into cubic yards, the unit commonly used for ready-mix ordering. The allowance remains visible instead of being hidden in the answer.
Use case
Convert slab length, width, and depth to cubic yards and keep the selected allowance visible; structural design, reinforcement, supplier minimums, and code remain separate checks.
Estimate cubic yards for a rectangular slab using feet, inches, and an explicit ordering allowance.
Build a reliable scenario
Concrete Calculator helps you check a specific home projects question with figures that apply to you. Estimate cubic yards of concrete from slab length, width, depth, and a waste allowance you choose. Convert slab length, width, and depth to cubic yards and keep the selected allowance visible; structural design, reinforcement, supplier minimums, and code remain separate checks. Estimate cubic yards for a rectangular slab using feet, inches, and an explicit ordering allowance. The page keeps the method and limits visible so the result can be understood, compared, and checked instead of treated as an unexplained answer.
Prepare Slab length, Slab width, Slab depth and Waste allowance. Measure the slab length and width in feet. Enter the uniform depth in inches. Choose an allowance for site variation and ordering. Confirm structural dimensions and supplier minimums before ordering. Keep units, dates, currency, and time periods consistent.
The stated method is: Cubic yards = length ft × width ft × (depth in ÷ 12) ÷ 27, then the entered allowance is added. Change one assumption at a time to see which input drives the result, then compare scenarios on the same basis.
A rectangular slab with uniform depth; grade variation, footings, beams, forms, and supplier minimums are not modeled. Use project plans and a qualified professional for structural requirements, reinforcement, mix, placement, and code compliance.
Source and update
Last reviewed: 2026-08-10
NIST — International System of Units guidanceConvert depth to feet, multiply all dimensions for cubic feet, then divide by 27.
Site conditions can require an allowance, but the appropriate amount depends on the project and supplier.
No. Thickness and reinforcement must come from the appropriate project design or professional.
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