Concrete Calculator
Estimate the volume of concrete and number of bags you need. Enter your slab or footing dimensions and get instant results.
Unit System
Volume
Cubic Yards
0.00
Cubic Meters
0.00
Bags Needed
40 lb
0
bags
60 lb
0
bags
80 lb
0
bags
About This Calculator
This concrete calculator helps you estimate the volume of concrete needed for slabs, footings, walls, and columns. It converts your length, width, and depth measurements into cubic yards and cubic meters, then tells you how many pre-mixed bags you need. Standard bag yields are used: a 40 lb bag covers 0.011 yd³, a 60 lb bag covers 0.017 yd³, and an 80 lb bag covers 0.022 yd³. The optional 10% waste factor accounts for spillage, uneven subgrade, and over-excavation.
FAQ
How thick should a concrete slab be?
A standard residential slab (patio, sidewalk) is typically 4 inches thick. Driveways and garage floors usually need 5 to 6 inches. For heavy loads or commercial use, 6 inches or more with rebar reinforcement is recommended.
What does the 10% waste factor cover?
The waste factor accounts for spillage during pouring, uneven ground that requires extra fill, slight over-excavation, and material left in the mixer or wheelbarrow. For complex shapes or sloped ground, you may want even more than 10%.
Should I use bags or ready-mix delivery?
Pre-mixed bags are practical for small projects under about 1 cubic yard. For larger pours, ordering ready-mix concrete from a truck is more cost-effective and ensures consistent quality. Most trucks deliver a minimum of 1 yard.
How do I convert between cubic yards and cubic meters?
1 cubic yard equals approximately 0.7646 cubic meters. This calculator handles the conversion automatically for you.