Concrete calculator
You need
– cubic yards
– cu ft · – m³ · sq ft
- Ready-mix concrete ($160–$195/yd)
- –
- Installed by a contractor
- –
Short answer
Multiply length × width × thickness in feet and divide by 27 to get cubic yards, then add 5–10% for waste. A 10 × 10 ft slab 4 inches thick needs 1.23 cubic yards: 56 bags of 80 lb mix or 75 bags of 60 lb mix.
| Cubic yards | L × W × T (ft) ÷ 27 |
|---|---|
| 80 lb bag yield | 0.60 cu ft (45 bags per yard)[1] |
| 60 lb bag yield | 0.45 cu ft (60 bags per yard)[1] |
| 40 lb bag yield | 0.30 cu ft (90 bags per yard)[1] |
| Ready-mix price | $160–$195+ per cubic yard[2] |
| Thickness | Cubic yards | 80 lb bags | 60 lb bags |
|---|---|---|---|
| 4 in | 1.23 | 56 | 75 |
| 5 in | 1.54 | 70 | 93 |
| 6 in | 1.85 | 84 | 112 |
Calculators for every pour
- Slab calculator: patios, pads, shed and garage floors.
- Bag calculator: how many 40, 50, 60, 80 or 90 lb bags you need.
- Yardage calculator: how many cubic yards to order from a ready-mix plant.
- Footing calculator: continuous footings for walls and foundations.
- Sonotube calculator: round columns and piers.
- Post hole calculator: fence, mailbox and deck posts.
- Stairs calculator: steps and landings.
- Wall calculator: poured walls and stem walls.
- Driveway calculator and patio calculator with installed cost.
- Cubic yard calculator for concrete, gravel, soil or mulch.
After the pour, see how long concrete takes to cure.
How the calculator works
Every mode converts your dimensions to cubic feet, adds your waste allowance and divides by 27 for cubic yards. Bag counts use QUIKRETE's published yields: 0.30 cu ft for a 40 lb bag, 0.375 for 50 lb, 0.45 for 60 lb, 0.60 for 80 lb and 0.675 for 90 lb. Bag counts are rounded up. Material cost uses ConcreteNetwork's national ready-mix range of $160–$195 per cubic yard. For flatwork, the installed estimate multiplies the area by published per-square-foot ranges for the finish you pick.
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Step 1 of 3
Frequently asked questions
How do I calculate how much concrete I need?
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Multiply length × width × thickness, all in feet, to get cubic feet, and divide by 27 to get cubic yards. Add 5–10% for waste and uneven ground.
How many bags of concrete make a yard?
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A cubic yard is 27 cubic feet: about 45 bags of 80 lb mix (0.60 cu ft each), 60 bags of 60 lb mix (0.45 cu ft) or 90 bags of 40 lb mix (0.30 cu ft), based on QUIKRETE's published yields.
Should I buy bags or order ready-mix?
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Bags make sense up to about a cubic yard (45 bags of 80 lb mix). Beyond that, ready-mix delivered by truck is faster and gives a more even pour, though small loads may carry short-load fees.
Sources
- [1]QUIKRETE, Concrete Mix No. 1101 data sheet (bag yields) (current data sheet)
- [2]ConcreteNetwork.com, Concrete Prices (updated July 14, 2026)
- [3]ConcreteNetwork.com, How Much Does a Concrete Driveway Cost? (updated January 13, 2026)
- [4]ConcreteNetwork.com, Concrete Patio Cost (updated January 20, 2026)
- [5]ConcreteNetwork.com, Stamped Concrete Cost (reviewed January 26, 2026)
Prices are national ranges published by the sources above, not quotes. Your price depends on size, access, site preparation and local labor rates. The only way to know is to compare written quotes.