Concrete Volume Calculator

Cubic yards of concrete for a rectangular slab/footing OR a cylindrical column/sonotube — with waste factor.

Inputs

Slab math: L·W·D. Column math: π·(d/2)²·D.

8", 10", 12" sonotubes are most common.

Slabs: 4" patios, 4-6" driveways, 8-12" footings. Columns/piers: total depth below frost line, often 36-48".

Standard 5-10% buffer for spillage and uneven sub-grade.

Result

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How to use this calculator

  • Enter the length and width of the slab in feet.
  • Enter the depth (slab thickness) in inches — most patios are 4 in, driveways 4-6 in, footings 8-12 in.
  • Adjust the waste factor; 10% is a safe default for residential pours.

About this calculator

Concrete is sold and ordered by the cubic yard. To figure out how much you need, multiply length × width × depth — making sure all three are in the same units — then divide by 27 to convert cubic feet to cubic yards. Adding a small waste factor (5-10% is standard) covers spillage, uneven sub-grades, and the inevitable last-minute "we should pour the front step too".

Frequently asked

How thick should my concrete slab be?+
Patios and walkways: 4 inches. Driveways for cars: 4 inches. Driveways for trucks/RVs: 5-6 inches. Footings and structural slabs: 8-12 inches. Always check local code for footings.
Why do I need a waste factor?+
A few percent of every concrete order is lost to spillage from the chute, uneven sub-grade depth, and minor over-pours at edges. Ordering exactly the calculated amount almost always means a second small (and expensive) delivery.
Is the answer in cubic yards or tons?+
Cubic yards. Concrete is sold by volume, not weight. One cubic yard of concrete weighs about 4,050 pounds (~2 tons), but ordering is always in cubic yards.
How does this differ for fiber-reinforced or high-strength concrete?+
It does not — the volume calculation is purely geometric. The mix design (PSI, fiber content, admixtures) is specified separately when you place the order.
Can I round my order down to save money?+
Not recommended. Most plants charge a "short load fee" if you order below 1 yd³, and being short on concrete means a cold joint or a forced second delivery. Round up.

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