AtlasCalc🏗️ ConstructionbeginnerOffline
Concrete Calculator
Volume of concrete needed for slabs, footings, columns, or walls.
Inputs
Enter your values below.
Result
Your answer appears here.
Enter values and press Calculate — the result appears here.
How it works
The formula behind this calculator.
volume = length × width × thickness; bags = volume / 0.6 ft³ per 80-lb bag
- length, width
- Surface dimensions
- thickness
- Slab depth, typically 4–6 inches for patios
Order 5–10% more than the calculated volume for spillage and over-excavation. Concrete cures, not dries — keep it moist for 7 days.
Example: 10 ft × 10 ft × 4 in slab → 33.3 ft³ → ~56 80-lb bags
Ref: Standard ready-mix concrete densities
Tips
- 💡 Always order 5–10% more concrete than your calculation. Spillage, over-excavation, and slab thickness variations add up.
- 💡 Concrete cures, not dries. Keep it moist for 7 days for maximum strength.