MATERIAL AND PROJECT ESTIMATES
Concrete Calculator
Estimate cubic yards of concrete from slab length, width, depth, and a waste allowance you choose.
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Your result
Ready when you are.
Enter your values and select Calculate. Your result stays on this device.
How it works
Cubic yards = length ft × width ft × (depth in ÷ 12) ÷ 27, then the entered allowance is added.
Assumptions
A rectangular slab with uniform depth; grade variation, footings, beams, forms, and supplier minimums are not modeled.
About this calculator
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.
How to use it
- 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.
Use case
concrete calculator: a clear planning check
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.
Source and update
Last reviewed: 2026-08-10
NIST — International System of Units guidanceFrequently asked questions
How are cubic yards of concrete calculated?
Convert depth to feet, multiply all dimensions for cubic feet, then divide by 27.
Should I add extra concrete?
Site conditions can require an allowance, but the appropriate amount depends on the project and supplier.
Does this determine slab thickness?
No. Thickness and reinforcement must come from the appropriate project design or professional.
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