Cement Calculator
Calculate concrete volume, materials, and costs for any construction project.
Project Dimensions
Standard slab: 4 inches
Concrete Mix Details
Recommended: 3000 PSI
10% is standard
Cost Factors
Concrete Requirements
Total Volume
Including 10% waste
Bags Needed
80 lb bags
Total Cost
$7.50/sq ft
Material Details
Cost Breakdown
Bulk vs Bags Comparison
Consider bulk delivery for this project - you'll save $693.44 and reduce labor!
How it works
A cement calculator estimates the volume of concrete (cement, sand, aggregate, and water) for a pour, then the bags or materials needed. Volume is length × width × depth; you convert to cubic yards and apply the mix ratio.
Volume to material
Cubic feet = length × width × depth Cubic yards = cubic feet ÷ 27
- length, width
- area dimensions in feet
- depth
- thickness in feet
Worked example
- Pad 8 ft × 6 ft
- 5 inches deep = 0.417 ft
- Cubic feet = 8 × 6 × 0.417 = 20.0
- Cubic yards = 20.0 ÷ 27
≈ 0.74 cubic yards of concrete.
Good to know
- Cement is the binder; concrete is the finished mix of cement, aggregate, and water.
- A typical 80-lb bag of pre-mix yields about 0.6 cubic feet.
- Order a little extra — running short mid-pour leaves a cold joint.
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Frequently Asked Questions
What is the difference between cement and concrete?
Cement is the binding powder (usually Portland cement); concrete is the finished material made by mixing cement with sand, gravel, and water. If you need the volume of finished concrete for a slab or footing, use our Concrete Calculator — this page focuses on the cement and mix side.
What is a standard concrete mix ratio?
A common general-purpose mix is about 1 part cement, 2 parts sand, and 3 parts gravel by volume, with roughly half a part of water adjusted for workability. Stronger structural mixes use more cement; mortar for block work omits the gravel.
How many bags of ready-mix make a cubic yard?
An 80-lb bag of ready-mix concrete yields about 0.6 cubic feet, so a cubic yard (27 cubic feet) takes roughly 45 bags. With 60-lb bags (about 0.45 cubic feet each) plan on about 60 bags per cubic yard.
How much extra material should I order?
Add 5-10% for simple pours and 10-15% where the subgrade is uneven or forms are complex — running short mid-pour creates a weak cold joint that costs far more than the spare bags.
When should I order ready-mix delivery instead of bags?
Above roughly one cubic yard, mixing bags by hand becomes slow and inconsistent; most suppliers deliver truck-mixed concrete from about one yard upward, which also gives a more uniform cure for slabs and driveways.