Foundation Calculator

Calculate concrete for foundation footings

Concrete Needed

5.19 yd³

Perimeter

140.0 ft

80lb Bags

234

Est. Cost

$648

Units

Length (ft)

Width (ft)

Foundation Depth (ft)

Wall Width (ft)

Cost per Cubic Yard ($)

Perimeter

140.0 ft

Volume

140.0 cu ft

80lb Bags

234

Est. Cost

$648

Material Requirements

Concrete Volume5.19

80lb Bags234

60lb Bags312

Bag Options Comparison

80lb Bags

234

Fewer trips

60lb Bags

312

Easier to carry

Estimated Cost$648

What You'll Need

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Example Calculations

1Standard Home Foundation (40 × 30 ft)

Inputs

Length40 ft

Width30 ft

Foundation Depth1 ft

Wall Width1 ft

Cost per Cubic Yard$125

Result

Concrete Needed5.19 cubic yards

Perimeter140.0 ft

Volume140.0 cu ft

80lb Bags234

60lb Bags312

Estimated Cost$648

Perimeter = 2 × (40 + 30) = 140 ft. Volume = 140 × 1 × 1 = 140 cu ft. Cubic yards = 140 / 27 = 5.19. 80lb bags = ceil(5.19 × 45) = 234. 60lb bags = ceil(5.19 × 60) = 312. Cost = 5.19 × $125 = $648.

2Large Garage Foundation (24 × 24 ft, 1.5 ft deep)

Inputs

Length24 ft

Width24 ft

Foundation Depth1.5 ft

Wall Width1 ft

Cost per Cubic Yard$125

Result

Concrete Needed5.33 cubic yards

Perimeter96.0 ft

Volume144.0 cu ft

80lb Bags240

60lb Bags320

Estimated Cost$667

Perimeter = 2 × (24 + 24) = 96 ft. Volume = 96 × 1 × 1.5 = 144 cu ft. Cubic yards = 144 / 27 = 5.33. 80lb bags = ceil(5.33 × 45) = 240. 60lb bags = ceil(5.33 × 60) = 320. Cost = 5.33 × $125 = $667.

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Frequently Asked Questions

How do you calculate concrete for a foundation?

Foundation concrete = Perimeter × Wall width × Depth. For a 40x30ft building with 1ft wide, 1ft deep footings: Perimeter = 140ft, Volume = 140 × 1 × 1 = 140 cubic feet = 5.2 cubic yards.

Measure all four sides and add to get total perimeter – a 40×30 ft building = 140 linear feet
Convert depth from inches to feet before multiplying (e.g., 18 in = 1.5 ft)
Always divide cubic feet by 27 to convert to cubic yards for ordering
Add 10% waste factor – 5.2 yd³ becomes 5.72 yd³, round up to 6 yd³

How deep should a foundation be?

Foundation depth depends on climate and load. Typical depths: 12-18 inches for light structures, 24-48 inches below frost line for homes. Consult local building codes for requirements.

Frost line depth: 12 in (zone 6–10), 36 in (zone 5), 48–60 in (zones 3–4)
IRC code requires footings at least 12 in below undisturbed ground for single-story homes
Two-story homes typically need 24 in wide footings vs 16 in for single-story
Garage slabs need a thickened edge (turned-down footing) at least 12 in deep and 12 in wide

Structure Type	Min Depth	Min Width
Shed / Light Structure	12–18 in	8–12 in
Single-Story Home	Below frost line	16 in
Two-Story Home	Below frost line	24 in
Detached Garage	12 in (turned-down)	12 in

How many bags of concrete make a cubic yard?

About 45 bags of 80lb concrete or 60 bags of 60lb concrete make 1 cubic yard. For larger projects, ready-mix concrete is more economical than bags.

One 80 lb bag yields 0.6 ft³, so 27 / 0.6 = 45 bags per cubic yard
One 60 lb bag yields 0.45 ft³, so 27 / 0.45 = 60 bags per cubic yard
Ready-mix is cheaper above 1 yd³ – 45 bags × $5 = $225 vs $125–$150 for ready-mix
Mixing 45 bags by hand takes 8–10 hours; rent a mixer for $50–$75/day to cut that in half

How much does foundation concrete cost?

Ready-mix concrete costs $100-150 per cubic yard delivered. Bagged concrete costs $3-5 per 80lb bag ($135-225 per yard). Labor and forming add significant costs to the total project.

Ready-mix delivery fee: $50–$100 flat plus $10–15 per mile beyond 20 miles
Short-load surcharge: $50–$75 per yd³ for orders under 5 yd³
Forming and rebar labor: $5–10 per linear foot of footing
Total foundation cost (with labor): $6–12 per linear foot for standard residential footings
Saturday delivery adds $100–$200; schedule pours mid-week to save

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Last Updated: Mar 26, 2026

This calculator is provided for informational and educational purposes only. Results are estimates and should not be considered professional financial, medical, legal, or other advice. Always consult a qualified professional before making important decisions. UseCalcPro is not responsible for any actions taken based on calculator results.

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