Concrete Calculator

Estimate the volume of concrete needed for a slab, footing, or column, plus the number of 60/80 lb bags.

Reviewed & updated:
Result breakdownCement (~15%): 15 (15.0%); Sand (~30%): 30 (30.0%); Aggregate (~55%): 55 (55.0%)
Volume
1.23 yd³
Cubic yards1.23 yd³
Cubic feet33.33 ft³
60 lb bags needed75
80 lb bags needed56

Results are estimates for general information only and are not professional financial, medical, tax, or legal advice. Read the full disclaimer.

How it works

Volume = length · width · thickness (in matching units). 1 yd³ ≈ 27 ft³.

Example

10 ft × 10 ft × 4 in slab → 33.3 ft³ ≈ 1.23 yd³.

Frequently asked questions

How many bags per yard?
About 45 × 80 lb bags or 60 × 60 lb bags per cubic yard.
Include waste?
Add 5–10% for spillage and uneven ground.
Ready-mix vs bags?
Ready-mix is cheaper above ~1 yd³.
What thickness for a driveway?
Typically 4 inches for passenger cars; 6 for trucks.

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