Concrete Calculator
CalculatingConcrete.com is a free suite of concrete calculators. Estimate exactly how much concrete you need — in cubic yards, cubic feet, cubic meters, and 40, 60, or 80 lb bags — for slabs, footings, walls, tube forms, stairs, and more. Pick a calculator below to get an instant, accurate estimate.
Concrete calculators
Every tool returns the volume and the number of bags you need, with a waste allowance built in. Choose the one that matches your pour:
- Slab CalculatorYards and bags for a rectangular slab.
- Yardage CalculatorConvert length, width, and depth into cubic yards.
- Bag CalculatorHow many 40, 60, or 80 lb bags you need.
- Block CalculatorBlock and mortar counts for a wall.
- Pad CalculatorConcrete for AC, shed, and hot-tub pads.
- Footing CalculatorFootings, foundations, and post holes.
- Weight CalculatorWeight of concrete in pounds and tons.
- Mix CalculatorCement, sand, and gravel for a mix ratio.
- Sonotube CalculatorConcrete for round tube forms and piers.
- Stairs CalculatorConcrete for steps and a landing.
- Driveway CalculatorYards and bags for a driveway slab.
- Wall CalculatorConcrete for poured and foundation walls.
- Square Footage CalculatorConcrete from a known floor area.
- Crushed Concrete CalculatorTons of crushed concrete or gravel base.
- Self-Leveling CalculatorBags of self-leveling underlayment.
How to calculate concrete
Concrete is sold by the cubic yard, so estimating a job comes down to finding its volume. Measure the length, width, and thickness of the pour, convert everything to feet, multiply them together for cubic feet, then divide by 27 to get cubic yards:
Cubic yards = (Length ft × Width ft × Thickness ft) ÷ 27
For example, a 10 ft × 10 ft slab at 4 inches thick is 10 × 10 × 0.333 = 33.3 cubic feet, or about 1.23 cubic yards. Add 5–10% for waste before you order. Our guides walk through the full method in detail:
- How to calculate concrete — the step-by-step method, formulas, and worked examples.
- How much concrete do I need? — sizing slabs, footings, and posts.
- How many bags of concrete in a yard? — the full 40/60/80 lb bag chart.
Brand calculators
Working with a specific bagged mix? Use a brand calculator to get the exact bag count by product and bag size.
Concrete guides
New to estimating concrete? These plain-English guides cover the formulas and the math behind every calculator.