Foundation Calculator
Estimate concrete volume, rebar, and cost for foundation walls
Length of the foundation footprint
Width of the foundation footprint
Height of the poured foundation wall
Thickness of the concrete wall
Rebar
—
ft
Concrete
—
cu yd
Estimated Cost
—
USD
Disclaimer: Results are estimates based on standard formulas. Not a substitute for professional advice from a licensed contractor, engineer, or architect. Verify all calculations before making purchasing or construction decisions.
How to Use This Calculator
A solid foundation starts with accurate material takeoffs. Order too little concrete and you'll short-pour the wall; order too much and you pay for wasted yardage.
- Measure the exterior length and width of your foundation footprint
- Enter the wall height (typical 8 ft) and thickness (typical 8 in)
- Review concrete volume and rebar length
- Use the cost estimate to compare foundation quotes
Expert Insights
Smart analysis for your Foundation project
Rebar Layout
Foundation walls typically run 4 continuous bars around the perimeter, spaced 24-48 inches on center. Our estimate uses a 4-bar baseline for the full run.
Cost per Yard
Installed poured concrete runs roughly $150 per cubic yard including forming, pumping, and finishing. Prices rise for difficult access or short loads.
Thickness & Depth
8-inch walls handle most single-story homes. Two-story builds or expansive clay soils usually require 10-inch walls and deeper footings per IRC.
Calculation Formula
Perimeter = 2 x (House length + House width)
Wall volume (cu ft) = Perimeter x Wall height x (Wall thickness / 12)
Concrete (cu yd) = Wall volume / 27
Rebar (ft) = ceil(Perimeter x 4)
Estimated cost = ceil(Concrete x $150 per cu yd)
Foundation Wall Type Comparison
| Foundation Type | Typical Thickness | Rebar Spacing | Cost per Cu Yd | Best For |
|---|---|---|---|---|
| Poured Concrete (8") | 8 inches | 24" o.c. | $130-170 | Standard residential |
| Poured Concrete (10") | 10 inches | 18" o.c. | $140-180 | 2-story / heavy loads |
| Concrete Block (CMU) | 8 inches | 32" o.c. | $110-150 | Budget builds |
| ICF (Insulated Forms) | 11-13 inches | 16" o.c. | $180-230 | Insulated basements |
| Precast Panel | 6-8 inches | per eng. | $160-210 | Fast install |
Authority References
Our calculations are based on guidelines and standards from these authoritative sources:
- American Concrete Institute (ACI) — ACI 332 Residential Code Requirements for Structural Concrete. Learn more
- International Residential Code (IRC) — Chapter 4 — Foundations. Learn more
- Portland Cement Association (PCA) — Residential Foundation Design. Learn more
Frequently Asked Questions
How much concrete do I need for a foundation?
Multiply the wall perimeter by height and thickness, then divide by 27 to convert cubic feet to cubic yards. A 40x30 ft home with 8 ft, 8-inch walls needs about 13-14 cubic yards of concrete.
How much rebar goes in a foundation wall?
Foundation walls typically use 4 continuous vertical or horizontal bars around the perimeter. Total length is roughly the perimeter multiplied by 4, spaced 24-48 inches on center.
How thick should a foundation wall be?
Most single-story homes use 8-inch poured concrete walls. Two-story homes or heavy clay soils often require 10-inch walls per IRC Chapter 4.