Concrete Volume Calculator
Slabs, footings, columns, walls, and stairs → cubic yards, cubic meters, and bag count.
Volume formulas+
Slab / footing: V = L × W × T
Wall: V = L × H × T
Column (round): V = π × (D/2)² × H
Stairs: V ≈ ½ × Riser × Tread × Steps × Width
Then × (1 + waste %). 1 yd³ = 27 ft³ = 0.7646 m³.
Volume estimate only. Mix design (PSI, slump, aggregate, admixtures) and reinforcement must be specified by a structural engineer.
Frequently asked questions
How much waste should I add?+
Industry standard is 10% waste for pump trucks on flatwork and 5% for wheelbarrow placement. Add more for complex geometry, slope, or first time using a contractor.
How many bags of concrete per cubic yard?+
An 80 lb bag yields ~0.60 ft³ → ~45 bags/yd³. A 60 lb bag yields ~0.45 ft³ → ~60 bags/yd³. For anything over ~1 yd³ order ready-mix instead of bagging.
When should I order ready-mix?+
Over about 1 cubic yard. Below that, the mixing labor and stoppage cost more than the ready-mix delivery minimum (typically 1 yd³ + short-load fee).
Does this include rebar?+
No, concrete volume only. Rebar takeoff depends on cover, bar spacing, lap splices, and chairs — best done from the structural drawings.
What about footings with a key or stem wall?+
Use the footing input for the spread footing, then add a wall input for the stem wall. Sum the two.
Slab on grade thickness?+
Residential: 4 in. Light commercial / garage: 5-6 in. Industrial / warehouse: 6-8 in with proper subbase and joint design — coordinate with a structural engineer.