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Concrete

Foundation Calculator USA 2026

Estimate concrete volume for a poured-wall foundation, including footings and stem walls.

Reviewed by BuildMate Editorial Team Construction Researchers Updated March 2026 2 min read Fact-checked

Used by

250,000+ homeowners

Avg. time

~15 seconds

Updated

2026

Accuracy

Pro estimation

Works on: Desktop Tablet Mobile No registration required
Unit system

Enter your measurements

Results

Volume

640 ft³

Cubic yards (with 10% waste)

26.07 yd³

Truck loads (10 yd³ per)

3

Calculation steps
  1. 1.Volume = 120 × 8 × (8/12) = 640.0 ft³
  2. 2.Yards with 10% waste = 23.70 × 1.10 = 26.07

Includes a standard waste allowance. Verify with your supplier before ordering.

Stored on this device — no account needed.

What this calculator does

Estimates the volume of ready-mix concrete you need — in cubic yards, cubic meters and 60/80 lb bag counts — plus a 10% waste allowance so you don't run short mid-pour.

When to use it

  • Planning a slab, patio, footing, driveway or sidewalk pour.
  • Comparing bagged vs. ready-mix truck pricing.
  • Sizing rebar, mesh and vapor barrier by area.

Common mistakes

  • Forgetting to convert thickness from inches to feet before multiplying.
  • Ordering exact volume with zero waste — always add 5–10%.
  • Ignoring compaction: over-excavated subgrade sinks the finished slab.

Pro tips

  • Order 10% extra for slabs, 15% for uneven ground or complex forms.
  • For driveways, use 6" thickness and #4 rebar at 18" on-center.
  • Pour early morning in summer to avoid flash-set from heat.
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Disclaimer: Estimates based on 2026 RSMeans USA data. Actual quantities vary by site conditions, waste and installer practices. Verify with your supplier or contractor before ordering.

How it works

  1. 1Enter the building perimeter in feet.
  2. 2Enter wall height and thickness.
  3. 3Add 10% waste for over-excavation and forming.

Formula

Volume = Perimeter × Height × Thickness

Worked example

120 ft perimeter × 8 ft × 0.67 ft (8") = 643 ft³ = 23.8 yd³.

Frequently asked questions

How thick for a residential foundation?

8" for single-story, 10" for two-story homes.

How deep does the footing go?

Below the frost line — 12–48" depending on climate zone.

Is the Foundation Calculator free to use?

Yes — every BuildMate calculator is 100% free, requires no signup and works offline once the page has loaded.

How accurate are these estimates?

Formulas follow 2026 industry standards (RSMeans, ICC and manufacturer specs). Real-world results vary by site conditions, waste and installer practices — always get 2–3 written quotes from licensed pros before committing.

Can I save my calculation?

Yes. Hit the Save button after you run an estimate — it's stored on this device (no account needed) and you can access it anytime from the Saved drawer.

Can I compare two projects side-by-side?

Yes. Add estimates to Compare and open the Compare drawer to see them side-by-side, then use Download PDF or Email to share the comparison.

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