Turn concrete volume into bag counts
Concrete Bag Calculator
Use this concrete calculator for bags to estimate a slab, footing, wall, or round pour. Enter the volume and the mixed yield printed on your product to calculate whole bags; common bag sizes are editable examples.
Slab / pad estimate
Measurement system: Imperial. Planning estimate based on the dimensions and allowance shown below.
Build your estimate
Choose a shape, enter measured dimensions, then review every step.
Enter the dimensions of the concrete itself. This estimate does not subtract posts or wall openings.
Bag yields and product settings
Yield differs by product. These common examples are editable.
Bag counts are rounded up. The 40, 50, 60, and 80 lb rows show common US products; use the package yield for your product.
Optional: price your materials
Enter local prices. No regional or supplier price is assumed.
Material estimate only. Delivery, taxes, labor, and supplier minimums are not included.
Calculation and assumptions
Divide the order volume by mixed yield per bag
Worked example: 10 × 10 ft slab, 4 in thick
- The net volume is 33.33 ft³ (1.23 yd³).
- At a chosen 10% allowance, the planning volume is 36.67 ft³.
- At 0.60 ft³ mixed yield per bag, 36.67 ÷ 0.60 rounds up to 62 bags.
Check the yield on the exact package
- Weight alone does not define mixed volume; different products and formulations have different yields.
- The common 40, 50, 60, and 80 lb rows are illustrative editable examples, not a guarantee for every brand or market.
- For a large pour, compare bagged material, labor, water, mixing time, and delivery with a ready-mix quote.
All example quantities are geometry and arithmetic illustrations. Confirm measurements, product yields, ordering rules, and project requirements with your plans and supplier.