Concrete Calculators

80 lb Concrete Bag Calculator

Estimate how many 80 lb bags of concrete mix are needed for a slab, footing, wall, or post hole.

Formula shown Updated 2026-05-20 Estimate only

Calculator

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Formula

How this estimate works

80 lb bags = cubic feet needed / 0.60, rounded up

One cubic yard is 27 cubic feet, or about 45 standard 80 lb bags before waste.

80 lb bag yield

A common planning yield for an 80 lb concrete bag is about 0.60 cubic feet. Divide the total cubic feet by 0.60 and round up to estimate bag count.

Weight and handling

80 lb bags reduce the number of bags but are heavy to lift repeatedly. For small jobs that is manageable, but larger projects may call for ready-mix.

Assumptions used

  • The calculator uses 0.60 cubic feet as a planning yield for an 80 lb bag.
  • Actual yield can vary by brand, mix, and water amount.
  • Bag count is rounded up to whole bags.

Before you order materials

  • Verify the yield on the product label.
  • Plan enough labor for mixing and placing heavy bags.
  • Buy a small surplus for hand-mixed jobs.

Frequently asked questions

How many cubic feet are in an 80 lb bag?

A common estimate is about 0.60 cubic feet per 80 lb bag, but check the specific product label.

How many 80 lb bags make a cubic yard?

Using 0.60 cubic feet per bag, one cubic yard is about 45 bags before waste.

Should I buy extra bags?

For small pours, buying one or two extra bags can prevent delays if measurements or subgrade depth vary.