Calculate exactly how much concrete you need for slabs, footings, columns, steps, or walls — in cubic yards, bags, and cost.
Select the concrete form type and enter dimensions
Choose bag mix strength and enter price per bag
Typically add 5–10% for waste and spillage
Same area at different concrete thicknesses
| Thickness | Cu Yards | 60-lb Bags | 80-lb Bags | Ready-Mix Cost |
|---|
Cubic Yards
Bags Needed
Bag Cost
Ready-Mix Cost
Volume (ft³)
Weight (lbs)
2,500 PSI
Light Use
Patios, walkways
3,000 PSI
Standard
Slabs, footings
3,500 PSI
Heavy Use
Driveways, garages
4,000 PSI
Commercial
Structural, beams
5,000 PSI
High-Strength
Bridges, columns
Always Add 10% Extra
Order at least 10% more than calculated. Concrete can't be returned once mixed, and running short mid-pour is expensive. For slabs over 50 yd³, order 5%.
Bags vs Ready-Mix
Bags are cost-effective under 1 yd³. Above 1 yd³, a ready-mix truck is typically cheaper per yard and gives a more consistent mix for structural work.
Curing Time
Keep concrete moist for at least 7 days. Concrete reaches ~70% strength in 7 days and full design strength at 28 days. Do not load heavy traffic before 28 days.