Concrete Bag Calculator
Convert a required concrete volume into an estimated number of premixed concrete bags.
Planning estimate only. Verify product specifications, field measurements, safety requirements, and applicable codes before buying or building.
Reviewed September 6, 2026Runs in your browser
Enter your numbers
How this calculator works
Bags = required cubic feet × (1 + waste percentage) ÷ yield per bag, rounded up to a whole bag.
Worked example
Twelve cubic feet with 10% extra needs about 30 60-lb bags at 0.45 cubic feet per bag.
Sources & assumptions
The selectable 60-lb and 80-lb yields follow QUIKRETE Concrete Mix product data. Other products can have different yields.
Frequently asked questions
Why use the bag’s listed yield?
Mix designs and bag sizes vary. The manufacturer’s yield is more reliable than a generic conversion.
Can I use this for fence posts?
Yes, after calculating the total hole volume. Subtract post volume if the post occupies a meaningful part of each hole.