Concrete Calculator
Calculate concrete volume, bags needed, and project costs for slabs, driveways, and foundations
Calculate Concrete Requirements
Project Dimensions
Concrete Specifications
Standard concrete density is 150 lb/cu ft
Account for spillage and waste (5-10% typical)
Cost Estimation
Enter local price per bag for cost estimates
Concrete Requirements
Total Weight: 0 lbs
Bags without waste: 0.0 bags
With 5% waste factor: 0.0 bags (rounded up to 0)
Project Analysis
Example Calculation
Driveway Slab Project
Project: 20 ft × 30 ft × 4 inches thick driveway
Volume: 20 × 30 × (4/12) = 200 cubic feet
Cubic yards: 200 ÷ 27 = 7.41 cubic yards
Weight: 200 × 150 lb/cu ft = 30,000 lbs
60 lb bags needed: 30,000 ÷ 60 = 500 bags
With 5% waste: 500 × 1.05 = 525 bags
Cost Breakdown
525 bags × $4.50 per bag = $2,362.50
Cost per square foot: $2,362.50 ÷ 600 sq ft = $3.94/sq ft
Recommendation: Consider ready-mix delivery for this size project
Common Bag Sizes
60 lb bags are most common for DIY projects
Concrete Types
High-Strength
4000+ PSI
Driveways, foundations
Standard
2500-3000 PSI
Sidewalks, patios
Rapid-Set
Sets in 25-40 min
Quick repairs
Concrete Tips
Add 5-10% extra for waste and spillage
Consider ready-mix for 4+ cubic yards
Use 4-inch minimum thickness for slabs
Cure concrete for 28 days for full strength
Add reinforcement for structural loads
Understanding Concrete Calculations
How to Calculate Concrete Volume
Concrete volume is calculated by multiplying length × width × depth. The result gives you the cubic footage, which is then converted to cubic yards (the standard unit for concrete ordering) by dividing by 27.
Concrete Weight and Density
- •Standard concrete weighs approximately 150 lbs per cubic foot
- •One cubic yard of concrete weighs about 4,000 lbs
- •Lightweight concrete can weigh 100-120 lbs per cubic foot
- •High-density concrete can weigh 200+ lbs per cubic foot
Bags vs. Ready-Mix
When to Use Bags:
- • Small projects (under 1 cubic yard)
- • Remote locations
- • DIY projects with flexible timing
- • Repairs and small pours
When to Use Ready-Mix:
- • Large projects (4+ cubic yards)
- • Time-sensitive pours
- • Professional quality needed
- • Complex mixes required