Already know how much concrete you need? Enter the volume in cubic feet, cubic yards or cubic meters, and the calculator shows how many bags of pre-mixed concrete that takes in each common bag size. To work out the volume first, use the concrete slab calculator or the fence post concrete calculator.
How the concrete bag calculator works
- Volume with waste = your volume × (1 + waste %). The default is 10% for spills, uneven ground and forms that bow.
- Bags = volume with waste ÷ bag yield, rounded up to whole bags.
- The volume is converted to cubic feet first: 1 cubic yard = 27 cu ft, and 1 cubic meter = 35.3 cu ft.
Concrete bag yield
| Bag size | Yield per bag | Bags per cubic yard | Bags per cubic meter |
|---|---|---|---|
| 80 lb | 0.60 cu ft | 45 | 59 |
| 60 lb | 0.45 cu ft | 60 | 79 |
| 40 lb | 0.30 cu ft | 90 | 118 |
Worked example
A 4 × 4 ft landing poured 4 in thick holds 4 × 4 × 0.333 = 5.33 cu ft. With 10% waste that is 5.87 cu ft. 5.87 ÷ 0.60 = 9.8, so you need 10 bags of 80 lb, or 14 bags of 60 lb, or 20 bags of 40 lb.
Bags for common volumes (with 10% waste)
| Volume | 80 lb bags | 60 lb bags | 40 lb bags |
|---|---|---|---|
| 1 cu ft | 2 | 3 | 4 |
| 5 cu ft | 10 | 13 | 19 |
| 10 cu ft | 19 | 25 | 37 |
| ½ cu yd (13.5 cu ft) | 25 | 33 | 50 |
| 1 cu yd (27 cu ft) | 50 | 66 | 99 |
Step by step: from volume to bags
Tips before you buy
- Above about 1 cubic yard (45 bags of 80 lb), ready-mix delivery is usually cheaper and much less work.
- Fast-setting and other specialty mixes can yield a different amount per bag. Use the yield printed on the bag if it differs. See the concrete bag yield chart for standard mix.
- Keep bags dry and off the ground. Damp bags start to harden and lose strength.
- One 80 lb bag is heavy. Use a hand truck or wheelbarrow and lift with your legs.
