Quick Concrete Calculator

Calculate your concrete volume, required bags and cubic feet instantly for free.

  • 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 and click calculate

Quick Concrete Calculator lets you enter the length, width and thickness of any slab and instantly see three useful results: total cubic yards, how many 80‑lb bags you’ll need, and the volume in cubic feet. Knowing the cubic yards helps you compare bids, while the bag count tells you exactly how many mixes to order, avoiding shortages or excess. The cubic‑feet figure is handy for checking against material specifications. Because the calculator uses the standard conversion that one 80‑lb bag yields 0.6 ft³, the numbers are reliable for most residential projects. You can also convert the cubic yards to metric units if your supplier prefers, and the tool updates instantly as you adjust any dimension. Just type your dimensions, hit calculate, and read the three results to plan your purchase and budget with confidence.

Pro tips

  • Add about 10% extra for waste to avoid shortfalls
  • Round up the bag count to the next whole bag
  • Order bags in multiples of 5 to reduce shipping costs
  • Double‑check thickness conversion from inches to feet before entering

Real-life examples

  • A homeowner pouring a 12 ft × 16 ft patio 4 in thick
  • A contractor estimating concrete for a 30 ft × 40 ft warehouse floor 6 in thick
  • A DIYer needing the bag count for an 8 ft × 10 ft garden walkway 3 in thick

Case study

Sam needed to pour a 10 ft × 20 ft garage slab 5 in thick. Using the calculator, he saw he required 1.23 cubic yards, which translated to 73 bags of mix. He ordered 75 bags, avoided a costly delay, and finished on budget.

Frequently asked questions

How do I convert thickness from inches to feet?
Divide the inches by 12; the calculator does this automatically when you enter the thickness in inches.
Why does the bag count not match the exact volume?
Bags are sold whole; the result is rounded up to ensure you have enough mix.
Can I use this calculator for concrete with a different bag weight?
This tool assumes an 80‑lb bag that yields 0.6 ft³; for other weights you’d need a different conversion.
What is the difference between cubic yards and cubic feet?
One cubic yard equals 27 cubic feet; the calculator shows both for easy reference.
Do I need to include a waste factor in the results?
The calculator shows the raw volume; add about 10 % extra for waste when ordering.