Concrete Slab Calculator – Accurate Estimates for Every Project
This concrete slab calculator helps you estimate how much concrete you'll need for flatwork like patios, footings, shed foundations, garage slabs, and more. Get quick and accurate results in cubic yards and pre-mixed bag estimates based on your project’s dimensions.
How It Works
- Calculates volume in cubic feet
- Converts to cubic yards (used for ready-mix concrete delivery)
- Estimates how many 60 lb and 80 lb concrete bags are required
Just enter the length, width, and depth of your slab and the calculator instantly provides volume totals. Whether you're a DIY homeowner or professional builder, this tool simplifies concrete planning.
Concrete Volume Formula
(Length × Width × Depth in feet) ÷ 27 = Cubic Yards
Cubic Feet ÷ 0.45 = 60 lb bags
Cubic Feet ÷ 0.6 = 80 lb bags
Common Uses for Slab Concrete
- Garage slabs and carports
- Garden sheds and workshops
- Driveways and walkways
- Patios, decks, and outdoor entertaining areas
- Basement floors or foundations
Tips for Accurate Results
- Always measure twice before ordering concrete
- Round up your total slightly to cover waste, spillage, or over-excavation
- Plan for wheelbarrow access or pump trucks if pouring in hard-to-reach areas
- For large slabs, consider adding rebar or mesh reinforcement
FAQs About Concrete Slabs
How deep should my concrete slab be?
Most residential slabs range from 4–6 inches deep. Driveways may require thicker slabs (up to 6–8 inches) for heavy loads.
Should I use pre-mixed bags or order ready-mix concrete?
Pre-mixed bags work for small jobs under 1 yard³. For anything larger, ordering ready-mix is more efficient and cost-effective.
How do I calculate formwork and reinforcement?
This calculator focuses on concrete volume. For formwork, add a few inches around the perimeter. Reinforcement depends on load — consult with a builder or engineer if unsure.
Estimate With Confidence
Get your slab job right the first time. Use this calculator to confidently estimate your concrete needs and avoid shortfalls or over-ordering. Save time, reduce waste, and budget accurately with our free tool.
Need more project help? Check out our other tools like the Gravel Calculator, Asphalt Calculator, or Brick Calculator to plan your next build with precision.