Concrete Calculator

Calculate exactly how much concrete you need for your project

Standard slab thickness is 4 inches
Recommended 5-15% for spillage and over-excavation

Concrete Calculation Tips

  • Standard concrete density: 150 lbs per cubic foot
  • Concrete coverage: One 80-lb bag yields ~0.6 cubic feet
  • Ready-mix concrete: Typically sold by cubic yard (27 cubic feet)
  • Waste factor: Always add 5-15% extra for spillage and uneven subgrades
  • Thickness guidelines: Driveways 4-6", sidewalks 4", foundations 8-12"
Important Notes
  • This calculator provides estimates only
  • Actual concrete needs may vary based on site conditions
  • Consult with a professional for structural projects
  • Concrete prices vary by region and mix type

About Concrete Calculations

Concrete volume is calculated using basic geometric formulas:

  • Slabs/Walls: Length × Width × Thickness
  • Footings: Length × Width × Depth
  • Columns: π × Radius² × Height

All measurements are converted to feet before calculation:

1 cubic yard = 27 cubic feet
1 foot = 12 inches

Conversion Factors

  • 1 cubic yard = 27 cubic feet
  • 1 80-lb bag = ~0.6 cubic feet
  • 1 cubic foot concrete ≈ 150 lbs

Concrete Calculator FAQ

Our calculator provides accurate estimates based on standard geometric formulas and concrete density. However, several factors can affect actual concrete needs:

  • Site conditions: Uneven terrain may require more concrete
  • Formwork: Additional concrete may be needed for formwork gaps
  • Settlement: Some settling occurs during placement
  • Waste: Spillage and over-excavation increase needs

We recommend adding a 10-15% waste factor to your calculations to account for these variables. For critical structural projects, always consult with a professional engineer.

The choice between ready-mix concrete and bagged mix depends on your project size:

Project Size Recommended Approach
Less than 0.5 cubic yards Bagged concrete mix (40-80 lb bags)
0.5 to 2 cubic yards Consider trailer-delivered mini-mix
More than 2 cubic yards Ready-mix concrete truck delivery

Bagged mix pros: No minimum order, easier for small jobs, can mix as needed
Ready-mix pros: More consistent quality, faster placement, better for large volumes

Concrete costs vary by region and mix type, but here are typical price ranges:

  • Ready-mix concrete: $120-$200 per cubic yard
  • Bagged concrete mix (80-lb): $5-$8 per bag
  • Short load fee (under 10 yds³): $50-$150
  • Pump truck (if needed): $150-$300 per hour

Additional cost factors:

  • Strength: High-strength mixes cost more
  • Additives: Fibers, accelerators, or color increase price
  • Delivery distance: Longer distances may incur extra fees
  • Accessibility: Difficult sites may require special equipment

Our calculator provides a basic cost estimate at $150 per cubic yard, but check local prices for accurate budgeting.