Slab Cost Calculator

Calculate concrete slab volume, material needs and cost instantly for free.

  • Free
  • No sign-up
  • Instant results

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How to use it

  1. Enter length, width, and thickness in the fields provided.
  2. Enter the price per cubic yard of concrete.
  3. Click Calculate to view cubic yards, estimated cost, bags needed, and cubic feet.

What it does – The Slab Cost Calculator turns the dimensions you enter (length, width, thickness) into the exact concrete volume in cubic yards, then translates that volume into the number of 80‑lb bags and the total material cost at your price per cubic yard. Why it matters – Knowing the true volume prevents ordering too little (which stops work) or too much (which wastes money). How to read the results – Cubic yards is the raw volume you’ll order. Estimated cost multiplies that volume by your unit price. Bags shows how many 0.6 ft³ bags you need, and Cubic feet lets you compare against other projects. All results appear instantly, so you can adjust dimensions and see cost changes in real time. You can also save the calculation for future reference or share it with your contractor.

Pro tips

  • Add 5‑10% extra for waste and spillage.
  • Round up the bag count to the next whole bag to avoid shortfalls.
  • Order concrete a day before the pour to ensure freshness.
  • Double‑check thickness conversion from inches to feet before entering.

Real-life examples

  • A homeowner estimating concrete for a new garage floor.
  • A contractor pricing a backyard patio slab for a client.
  • A DIYer planning a concrete garden walkway and needing material totals.

Case study

Mike entered his 20 ft × 15 ft patio dimensions, 4‑inch thickness, and his supplier’s $150 per cubic yard price. The calculator showed 0.44 cubic yards, 7 bags, and a $66 cost, letting him order precisely and stay within budget.

Frequently asked questions

How do I convert thickness from inches to feet?
Divide the thickness in inches by 12 to get feet before the calculator processes the volume.
Why does the bag count differ from the cubic yards?
Bags are measured in cubic feet (0.6 ft³ each), so the calculator converts cubic yards to cubic feet then divides by 0.6.
Should I include a waste factor?
Yes, add 5‑10% to the bag count or volume to cover spillage and minor miscalculations.
What if my concrete price is per cubic foot?
Convert the price to per cubic yard by multiplying the per‑cubic‑foot price by 27, then enter that value.
Can I use the calculator for multiple slabs?
Enter the total combined length, width, and thickness for all slabs, or run separate calculations and add the results.