Last updated: March 17, 2026
Concrete Calculator
Calculate the amount of concrete needed for slabs, footings, columns, and other projects.
Results
Concrete Volume Formula
Calculate concrete volume in cubic yards:
- Volume (cubic ft) = Length × Width × (Thickness / 12)
- Volume (cubic yards) = Volume (cubic ft) / 27
- 80lb Bags = Volume (cubic yards) × 45
- 60lb Bags = Volume (cubic yards) × 60
Example Calculation
For a 10ft × 10ft slab with 4 inches thickness:
Volume = 10 × 10 × (4/12) = 33.33 cubic ft
Cubic Yards = 33.33 / 27 = 1.23 cubic yards
80lb Bags = 1.23 × 45 = 56 bags
60lb Bags = 1.23 × 60 = 74 bags
Frequently Asked Questions
How thick should a concrete slab be? ▼
Standard residential slabs are 4 inches thick. Driveways and areas with heavy loads should be 5-6 inches thick.
Should I order extra concrete? ▼
Yes, order 5-10% extra to account for spillage, uneven ground, and measurement variations.