Concrete Bags Calculator
Concrete Bags Calculator
If you already know the volume of concrete you need (in cubic feet), this tool tells you how many bags to buy at each common bag size — handy for comparing which size is most cost-effective or available at your local supplier.
Bag yield doesn't scale perfectly linearly with weight because of how the mix compacts, which is why a 40 lb bag yields about 0.30 cubic feet while an 80 lb bag yields about 0.60 — exactly double, in this case, but that's not guaranteed across every brand, so checking the actual yield printed on your specific bag is worth doing before finalizing a purchase count. Comparing all common sizes side by side (rather than just picking whatever's on the shelf) is genuinely useful for small jobs, where buying fewer, larger bags is usually both cheaper per cubic foot and less physically demanding to carry and mix.
- Imperial yields: 40 lb bag ≈ 0.30 cu ft, 60 lb ≈ 0.45 cu ft, 80 lb ≈ 0.60 cu ft. Example: 10 cu ft needs 34/23/17 bags respectively.
- Metric yields: 20 kg bag ≈ 0.010 m³, 25 kg bag ≈ 0.0125 m³. Example: 0.3 m³ needs 30 bags at 20 kg or 24 bags at 25 kg.
- Don't know your volume yet? Use the Concrete Calculator on this site first, in either unit system.
Which bag size should I choose?
Larger bags (80 lb) are usually more cost-effective per cubic foot but heavier to carry — 40 lb bags are easier to handle alone for smaller DIY jobs.
Should I buy extra bags beyond the calculated amount?
Yes — buying a few extra bags is standard practice to cover spillage, mixing losses, and minor measurement error.
Concrete Bags Calculator
If you already know the volume of concrete you need (in cubic feet), this tool tells you how many bags to buy at each common bag size — handy for comparing which size is most cost-effective or available at your local supplier.
Bag yield doesn't scale perfectly linearly with weight because of how the mix compacts, which is why a 40 lb bag yields about 0.30 cubic feet while an 80 lb bag yields about 0.60 — exactly double, in this case, but that's not guaranteed across every brand, so checking the actual yield printed on your specific bag is worth doing before finalizing a purchase count. Comparing all common sizes side by side (rather than just picking whatever's on the shelf) is genuinely useful for small jobs, where buying fewer, larger bags is usually both cheaper per cubic foot and less physically demanding to carry and mix.
- Imperial yields: 40 lb bag ≈ 0.30 cu ft, 60 lb ≈ 0.45 cu ft, 80 lb ≈ 0.60 cu ft. Example: 10 cu ft needs 34/23/17 bags respectively.
- Metric yields: 20 kg bag ≈ 0.010 m³, 25 kg bag ≈ 0.0125 m³. Example: 0.3 m³ needs 30 bags at 20 kg or 24 bags at 25 kg.
- Don't know your volume yet? Use the Concrete Calculator on this site first, in either unit system.
Which bag size should I choose?
Larger bags (80 lb) are usually more cost-effective per cubic foot but heavier to carry — 40 lb bags are easier to handle alone for smaller DIY jobs.
Should I buy extra bags beyond the calculated amount?
Yes — buying a few extra bags is standard practice to cover spillage, mixing losses, and minor measurement error.