Concrete Volume Calculator
Volume in cubic yards or cubic feet for any concrete shape
What is concrete volume calculator?
A concrete volume calculator computes the raw geometric volume of a concrete element. It’s the foundation under every other concrete calculator — bag counts, weights, and ready-mix orders all derive from volume. The math is shape-specific:
Rectangular prism (slab, footing, wall): length × width × thickness. Use feet for all three dimensions, or convert thickness from inches by dividing by 12. Volume comes out in ft³; divide by 27 for yd³.
Cylinder (column, sonotube): π × r² × h, where r is the radius (half the diameter). A 10 in diameter sonotube 4 ft tall: π × (5/12)² × 4 = 2.18 ft³ = 0.08 yd³.
Stairs: sum of step volumes, where each step is rise × run × width. A 4-step stair at 7.5 in rise × 11 in run × 36 in wide is 4 × (0.625 × 0.917 × 3) = 6.88 ft³.
Why two volume readouts? Cubic feet is the unit for engineering calcs (dead load = volume × 150 lb/ft³), small bag-mix estimates, and the formulas in textbooks. Cubic yards is the unit for ready-mix orders — every concrete plant bills in yards. The calculator outputs both because you’ll need both at different stages of a project.
Volume vs delivered concrete. The geometric volume is your net concrete in place. The gross order adds a waste factor (typically 10%) to cover spillage, uneven subgrade, and form absorption. On a 100 ft³ pour, you order 110 ft³ (~4.07 yd³). The calculator’s default is 10% waste; bump it to 15% for footings with rebar interference or rough subgrade.
Unit traps. Mixing inches and feet is the #1 source of volume errors. The calculator labels each input with its expected unit (ft for length, in for thickness) — don’t override it.
When to use a concrete volume calculator
- Engineering takeoff — For estimates and structural calcs, raw cubic-foot volume is what feeds dead-load formulas and material schedules. The calculator outputs both ft³ and yd³.
- Multi-shape pour — Compute volume per element (footing + column + slab) and sum. Each shape's math is shown alongside the total — useful for spec packages.
- Verify a vendor quote — When a contractor's quoted volume doesn't match your number, recompute by shape from the prints. Discrepancies usually trace to thickness assumptions or waste factor.
How to use the Concrete Volume Calculator
- Identify the shape — Slab and footing are rectangular prisms (L × W × H). Column is a cylinder (π × r² × h). Wall is a vertical rectangle. Stairs is a sum of treads.
- Use consistent units — The calculator handles imperial (feet, inches) and metric (meters, centimeters). Don't mix — pick one before entering values.
- Read both ft³ and yd³ — Ft³ for engineering load calcs and small estimates. Yd³ for ordering ready-mix. The calculator outputs both so you don't have to convert by hand.
- Verify with a hand check — For a rectangular prism, multiply the three dimensions and divide by 27 to get yd³. The calculator should match within rounding.
Worked examples
Slab: 20 × 20 ft × 6 in
Input: Slab tab: 20 ft × 20 ft × 6 in
Output: 7.41 cu yd / 200.0 cu ftSonotube: 12 in dia × 8 ft
Input: Column tab: 12 in dia × 8 ft
Output: 0.26 cu yd / 6.9 cu ftWall: 40 ft × 8 ft × 10 in
Input: Wall tab: 40 ft × 8 ft × 10 in
Output: 9.88 cu yd / 266.7 cu ft