Concrete Volume Calculator – How Much Concrete Do You Need?
Estimate concrete quantities for any project with our concrete volume calculator. Compute cubic yards or meters for slabs, columns, footings, and walls to avoid over-ordering.
Recommended: 5-10% for slabs, 10-15% for complex shapes
Concrete volume is just length × width × depth for rectangular shapes. For a 10×12 foot slab that's 4 inches thick: 10 × 12 × 0.33 = 40 cubic feet, or about 1.5 cubic yards. Add 10% for waste and you order 1.65 yards.
Volume Formulas
Slab/Footing: Length × Width × Depth
Wall: Length × Height × Thickness
Column: π × (diameter/2)² × Height
The waste factor matters more than people think. Spillage, over-excavation, and form bowing all eat concrete. A 10% waste factor means ordering 1.1 cubic yards for every 1 yard calculated. For complex forms or pump trucks, bump it to 15%.
| Project Type | Waste Factor | Why |
|---|---|---|
| Simple slab on grade | 5-7% | Minimal formwork, easy pour |
| Standard footings | 7-10% | Some trench over-excavation |
| Columns and walls | 10-12% | Form work complexity, spillage |
| Complex shapes/stamped | 12-15% | Cutting waste, pattern matching |
| Pump truck delivery | +3-5% | Concrete left in pump lines |
| Bag Size | Yield (cubic feet) | Yield (cubic yards) | Bags per Cubic Yard |
|---|---|---|---|
| 40 lb bag | 0.30 cu ft | 0.011 cu yd | 90 bags |
| 60 lb bag | 0.45 cu ft | 0.017 cu yd | 60 bags |
| 80 lb bag | 0.60 cu ft | 0.022 cu yd | 45 bags |
Yields are approximate and vary by brand and water content. Quikrete and Sakrete have slightly different formulations.
| Project | Dimensions | Volume (no waste) | With 10% Waste |
|---|---|---|---|
| 10×12 patio, 4" thick | 10′ × 12′ × 0.33′ | 1.48 cu yd | 1.63 cu yd |
| 24×24 garage slab, 5" thick | 24′ × 24′ × 0.42′ | 8.89 cu yd | 9.78 cu yd |
| Deck footing, 4 columns | 12" dia × 36" deep | 2.62 cu yd | 2.88 cu yd |
| Retaining wall | 20′ × 4′ × 1′ | 2.96 cu yd | 3.26 cu yd |
Frequently Asked Questions
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