Square Footage Concrete Calculator

Calculate concrete volume in cubic yards, 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

What it does: The Square Footage Concrete Calculator takes your slab dimensions—length, width, and thickness—and instantly tells you the total concrete needed in cubic yards, cubic feet, and the number of 80‑lb bags. Why it matters: Ordering the right amount saves money and prevents project delays; too little means a pause, too much adds unnecessary cost. How to read the results: Cubic feet is the raw volume, cubic yards is the industry‑standard for delivery, and bags let you compare against what you’ll actually purchase. The tool uses the standard 0.6 ft³ per 80‑lb bag, so the bag count reflects real‑world ordering. No hidden math—just clear numbers you can act on. You can also adjust for a 10% waste factor later, but the base numbers give you a solid starting point for budgeting and scheduling.

Pro tips

  • Add a 10% waste allowance to cover spillage and variations
  • Round the bag count up to the next whole bag
  • Check local delivery minimums before ordering
  • Convert thickness from inches to feet before entering

Real-life examples

  • Homeowner planning a 12‑ft patio slab
  • Contractor estimating concrete for a 20‑ft driveway
  • DIY enthusiast building a concrete garden bench base

Case study

Mike needed a 10 × 10 ft patio 4 in thick. Using the calculator he saw he required 1.24 cubic yards, 33.3 ft³, and about 56 bags, so he ordered exactly that amount, avoided a costly over‑order, and completed the pour on schedule.

Frequently asked questions

How many cubic yards of concrete do I need for a slab?
Enter the slab dimensions; the calculator converts the volume to cubic yards for you.
How many 80‑lb bags equal one cubic yard?
One cubic yard equals about 45 bags (27 ft³ ÷ 0.6 ft³ per bag).
Do I need to include waste in my calculation?
Add a 10% waste factor to the bag count for most residential projects.
Can I use the calculator for steps or curbs?
Yes, just measure each section’s length, width, and thickness and sum the volumes.
Is the calculator free to use?
Yes, it provides instant results at no cost and no sign‑up required.