Slab Concrete Calculator

Easily calculate concrete volume for slabs, footings, or walls. Get accurate bag counts and waste estimates for your project.

Slabs, Square Footings, or Walls

Volume

  • Cubic yards:1.23
  • Cubic meters:0.94
  • Cubic feet:33.33

Bags (approx.)

  • 60-lb bags:74.07
  • 80-lb bags:55.56

Assumes ~0.45 ft³ per 60-lb bag and ~0.60 ft³ per 80-lb bag. Add 5–10% waste.

Results will appear inside the calculator card above. You can also add 5–10% extra for waste.
Diagram

Tips

  • Add 5–10% extra for waste and uneven ground.
  • Confirm local building codes for thickness and reinforcement.
  • Choose 60lb or 80lb bags based on handling preference.

Slab FAQ

Q1How do I calculate concrete volume for a slab?›

Multiply length × width × thickness to get cubic feet, then divide by 27 for cubic yards. Our slab calculator does this automatically and also estimates 60lb or 80lb bag counts.

Q2Do I need rebar or mesh for a 4-inch slab?›

For patios and walkways, wire mesh or fiber-reinforced concrete is often enough. Driveways and thicker slabs usually require rebar reinforcement—always follow local building codes.

Q3What is the recommended slab thickness?›

Most residential patio slabs are 4 inches thick, while driveways need 5–6 inches to handle vehicle loads. Use our calculator to adjust thickness and see the difference in volume.

Q4How many bags of concrete do I need for 1 cubic yard?›

One cubic yard equals about 45 bags of 60lb or 60 bags of 80lb mix. The slab calculator converts cubic yards to bag counts for quick planning.

Q5Should I add extra concrete for waste?›

Yes, adding 5–10% extra is standard to account for spillage, uneven ground, and finishing. The calculator result includes this recommendation.