Utility
Concrete Calculator
Calculate how much concrete you need in cubic yards, cubic meters, and bags for slabs, columns, and stairs.
Enter dimensions and click Calculate
How is this calculated?
Slab: Volume = Length × Width × (Depth/12) cubic feet
Column: Volume = π × (Diameter/24)² × Height cubic feet
Cubic Yards = Cubic Feet / 27
Cubic Meters = Cubic Feet × 0.0283168
Bags: 80lb=0.6cf, 60lb=0.45cf, 40lb=0.3cfFAQ
Frequently asked questions
How do I calculate how much concrete I need?
Multiply length × width × depth to get cubic feet, then divide by 27 to convert to cubic yards. For columns, use π × radius² × height. This calculator handles these conversions automatically.
How many bags of concrete do I need?
An 80lb bag covers about 0.6 cubic feet, a 60lb bag covers 0.45 cubic feet, and a 40lb bag covers 0.3 cubic feet. Divide your total cubic feet by the coverage per bag.
How thick should a concrete slab be?
Standard residential slabs are 4 inches thick. Driveways should be 5-6 inches. Garage floors need 6 inches minimum. Heavy-use commercial slabs may require 8+ inches.
Should I order extra concrete?
Yes, order 5-10% more than calculated to account for spillage, uneven ground, and form irregularities. For complex shapes, consider ordering 10-15% extra.
What is the difference between cubic yards and cubic meters?
1 cubic yard = 0.7646 cubic meters. Most US concrete is sold by the cubic yard, while metric countries use cubic meters. This calculator shows both units.
Is this concrete calculator free?
Yes, completely free with no sign-up. All calculations happen in your browser — your data is never sent to any server.