🏗️ Concrete Calculator
Concrete projects require accurate volume calculation — too little results in incomplete work, too much means wasted money. This calculator computes exactly how much concrete you need and how many bags to order.
Volume in cubic feet
33.33 ft³
Volume in cubic yards
1.23 yd³
Volume in cubic meters
0.944 m³
Concrete bags (25kg)
50 zakken
Convert depth to feet: 4" ÷ 12 = 0.333 ft
Calculate volume in cubic feet: 10 ft × 10 ft × 0.333 ft = 33.33 ft³
Convert to cubic yards: 33.33 ft³ ÷ 27 = 1.23 yd³
Calculate concrete bags (25kg each): 0.944 m³ × 52 zackar/m³ = 50 zackar
Formula
Concrete volume (m³) = Length ft × Width ft × Depth ft ÷ 27 × 0.765. Bags = Volume m³ × 52 (for 25kg bags).
First calculate volume in cubic feet (length × width × depth in feet). Then convert to cubic yards (÷ 27) and then to cubic meters (× 0.765). Finally multiply by 52 because one cubic meter approximately contains 52 bags of 25kg concrete.
Steps
- 1Measure the length and width of the concrete project in feet.
- 2Determine the required depth in inches (typically 4" for driveways, 6" for foundations).
- 3Enter the values and the calculator computes the volume and number of bags.
- 4Order enough bags, plus 1-2 extra for spillage (mixing, shifts, etc.).
Recommended concrete depths
| Project type | Depth | Notes |
|---|---|---|
| Driveway | 4 inches | Min. 4", better 5-6" for heavy vehicles |
| Patio | 4 inches | 4" standard, deeper for frozen ground areas |
| Foundation | 6-8 inches | Deeper for large structures or soft soil |
| Pad/Post | 12+ inches | Much deeper for foundation stability |
Depths depend on local building codes and soil conditions.
commonMistakes
- Entering depth in centimeters when calculator expects inches — convert to inches first.
- Not accounting for ground prep — soil must be compacted, otherwise concrete can crack.
- Not accounting for bag mixing — ordering bags assumes concrete mix, not powder.
useCases
- Budgeting and material planning for large concrete projects — accurate volume means accurate budgeting.
- Delivery coordination — know how many bags you need before you order, prevent emergency deliveries.
- Accurate calculation of labor costs and estimates for contractors.