Cement Calculator
Enter project dimensions to calculate bags of cement needed.
Cement Calculator Formula
Enter length, width, and depth to calculate total volume. The calculator converts to bags of cement based on bag coverage size.
Understanding Cement Calculations
Cement vs. Concrete: Key Differences
Cement is a binding powder, not a finished building material. Concrete is a mixture of cement (10-15%), water (15-20%), sand (25-30%), and gravel aggregate (30-40%). Understanding this distinction matters for accurate ordering.
Cement Types and Strength Ratings
| Cement Type | ASTM Standard | Strength (28-day PSI) | Best Use |
|---|---|---|---|
| Type I (General Purpose) | ASTM C150 | 3,000-4,000 | Standard construction |
| Type II (Moderate Sulfate) | ASTM C150 | 3,000-4,000 | Sulfate-rich soil foundations |
| Type III (High Early) | ASTM C150 | 3,500+ (7-day) | Cold weather, fast-track |
| Type V (High Sulfate) | ASTM C150 | 3,000-4,000 | Severe sulfate exposure |
How Many Bags of Cement per Cubic Yard of Concrete?
- 3,000 PSI mix: 5 bags of cement per cubic yard (470 lbs cement).
- 4,000 PSI mix: 6 bags per cubic yard (564 lbs cement).
- 5,000 PSI mix: 7 bags per cubic yard (658 lbs cement).
For small projects, pre-mixed 80-lb bags are more practical. You need 45 bags per cubic yard.
Cement Storage and Shelf Life
Store bags off the ground on pallets, in a dry location. Properly stored cement lasts 3-6 months. Cement that has hardened into lumps is unusable. Buy only what you need for the current project.
Cement Calculator FAQ
For concrete mixing, you need 5-6 bags (94 lbs each) of Portland cement per cubic yard using a standard mix. Calculate project volume in cubic yards first, then multiply by bags per yard.
Cement is a powder ingredient (10-15% of the mix). Concrete is the finished product combining cement with water, sand, and gravel. You buy cement to make concrete.
A 10x10 foot slab at 4 inches thick requires 1.23 cubic yards of concrete. That takes 6-7 bags of Portland cement if mixing from scratch, or about 56 bags of 80-lb pre-mixed concrete.
A standard bag of Portland cement weighs 94 pounds. Pre-mixed concrete bags come in 40, 60, and 80-pound sizes.
Pure cement mixed with water (cement paste) cracks and has no structural strength. You must add sand and gravel to create concrete. The aggregates provide bulk and dimensional stability.
Concrete reaches 70% strength in 7 days and full design strength in 28 days. Keep the surface moist for the first 7 days for maximum strength.