Concrete Calculator

Cubic yards (or bags) needed for slabs, footings, and columns. Includes a 10% waste factor — the universal rule for pouring concrete.

Materials

With 10% waste — order this much

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Volume (no waste)

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Cubic feet

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Cubic meters

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If buying bags instead

80-lb bags (0.6 cuft each)

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60-lb bags (0.45 cuft each)

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40-lb bags (0.30 cuft each)

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Ready-mix vs bagged

For anything over ~1 cubic yard (≈ 60 bags of 80-lb), bagged concrete becomes brutal — you'll fight curing time and joint lines. Order ready-mix delivery if you can. The truck minimum is usually 1 cu yd, with a small "short load" fee under 3-4 yards.

Why the 10% waste

  • Subgrade depth isn't perfectly uniform — pour a 4" slab and you'll find some 4.5" spots.
  • Spillage during pour. Pumping wastes a few percent in the line.
  • Trucks don't deliver exact volumes — they round to the quarter yard.

Ordering 10% over avoids the worst outcome (running out mid-pour). The leftover is small; the cost of a partial second truck delivery is large.

Bag yields (Quikrete / Sakrete standard)

  • 80-lb bag: ~0.6 cu ft (45 bags = 1 cu yd)
  • 60-lb bag: ~0.45 cu ft (60 bags = 1 cu yd)
  • 40-lb bag: ~0.30 cu ft (90 bags = 1 cu yd)