Concrete Network Concrete Calculator

Instantly calculate cubic yards, bag count, and cubic feet for any concrete slab – free and instant.

  • Free
  • No sign-up
  • Instant results

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How to use it

  1. Enter length in feet
  2. Enter width in feet
  3. Enter thickness in inches
  4. Read cubic yards, bags, and cubic feet results

What it does – The Concrete Network Concrete Calculator turns the three dimensions you enter (length, width, thickness) into three practical numbers: total cubic yards of concrete, how many 80‑lb bags you’ll need, and the raw cubic‑foot volume. Knowing cubic yards is essential for ordering ready‑mix trucks, while the bag count tells you exactly how many retail bags to buy for small jobs. The cubic‑foot figure helps you compare against product specs or calculate waste. The tool uses the industry‑standard conversion that one 80‑lb bag yields about 0.6 ft³, so the results are reliable for residential slabs, driveways, or patio pads. Just plug in your dimensions and read the three results – no guesswork, no extra calculations. You can also save the numbers for a quick quote or share them with your contractor.

Pro tips

  • Add a 10% waste allowance to the bag total
  • Round up to the nearest whole bag to avoid shortfalls
  • Order a bit extra if the subgrade isn’t perfectly level
  • Double‑check that thickness is entered in inches, not feet

Real-life examples

  • Homeowner planning a 12 ft × 12 ft patio 4 in thick
  • Contractor estimating concrete for a 20 ft × 30 ft driveway
  • DIY hobbyist needing bag count for a garden stepping stone base

Case study

Mike needed a 10 ft × 15 ft slab 5 in thick for his garage floor. Using the calculator he saw he required 1.84 yd³ and 103 bags, so he ordered 110 bags to cover waste and got the job done on schedule.

Frequently asked questions

How do I convert the calculator’s result to ready‑mix truck volume?
Take the cubic yards result; most trucks are quoted per cubic yard, so order that amount.
Do I need to include a waste factor?
Yes, add about 10% to the bag count to cover spillage and minor over‑fill.
What if my slab thickness is in centimeters?
Convert centimeters to inches (1 cm ≈ 0.39 in) before entering.
Can I use the bag count for a mixed‑size project?
The bag count is based on 80‑lb bags; for larger projects you may order in bulk by cubic yard instead.
Why does the calculator show cubic feet if I only need bags?
Cubic feet lets you verify the volume and compare it to product specs before converting to bags.