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concrete

Concrete Cubic Feet Calculator

Calculate concrete cubic feet, cubic yards, and cubic meters.

Enter length and width in feet, thickness in inches.

Use Area when you already know square footage. Ramp uses different start and end thicknesses.

Quick estimates
Component templates

Suggested waste for this setup: 5-10%. Regular flatwork usually needs enough margin for forms, grade variation, and small measurement errors.

Cost planning uses the selected order unit. Delivery, short-load fee, and labor are extra.

Advanced cost

Labor range uses $4-$8 per ft² as a planning range.

Multi-section estimate

Add irregular areas, aprons, landings, or pads and BuilderCalc will total them.

Estimated concrete neededEnter dimensionsLength, width, and thickness are required before the estimate appears.
Example6 x 6 ft pad x 4 in = about 12.00 ft³ before waste

Cubic feet are useful for bag yield; divide by 27 to convert to cubic yards.

Last reviewed: May 12, 2026 by the BuilderCalc editorial team.

SSR formula reference

Concrete Cubic Feet Calculator formulas

These formulas are rendered in the server HTML so crawlers, LLMs, and users can read the method without running JavaScript. The interactive calculator can change the inputs, but the estimating math below is visible in the raw page source.

Volume (cubic feet) = Length x width x thickness (in inches / 12).

Volume (cubic yards) = Cubic feet / 27.

Bags (80-lb) = Cubic feet / 0.60, rounded up.

80-lb bag yields about 0.60 ft3, or 0.022 yd3.

Result Formula
Volume in cubic feet Length x width x thickness in feet
Thickness in feet Thickness in inches / 12
Volume in cubic yards Cubic feet / 27
80-lb bags Cubic feet / 0.60, rounded up
Ready-mix order Cubic yards x (1 + waste percent)

Standard PSI by application

Application Recommended PSI
Patio or walkway3,000 PSI
Garage floor, residential3,500 PSI
Driveway, cars3,500 to 4,000 PSI
Driveway, trucks or RVs4,000 to 4,500 PSI
Foundations and footings3,000 to 4,000 PSI, per plan and code

Bag yield reference

Bag size Common yield
80-lb bagAbout 0.60 ft3, or 0.022 yd3
60-lb bagAbout 0.45 ft3, or 0.017 yd3
50-lb bagAbout 0.375 ft3, or 0.0138 yd3
40-lb bagAbout 0.30 ft3, or 0.011 yd3

Cubic-foot planning

Concrete Cubic Feet Calculator planning notes

Cubic feet are useful for bag yield and small project math. Convert to cubic yards when comparing against ready-mix pricing.

Use feet for all dimensions

Thickness must be converted from inches to feet before multiplying by length and width. Four inches equals 0.333 feet.

Convert after the total

Add section volumes in cubic feet first, then convert the total to cubic yards or bag counts.

How to use it

Keep the estimate tied to field measurements

01

Use feet throughout

Convert thickness from inches to feet before multiplying. Four inches is one-third of a foot.

02

Add sections first

For irregular projects, add section volumes in cubic feet before converting to other units.

03

Convert to bags or yards

Use cubic feet for bag yield and cubic yards for ready-mix ordering.

Related calculators

Try the slab calculator Calculate concrete yards and bags for garage slabs, shed bases, pads, and flatwork. Need sidewalk concrete? Calculate concrete for sidewalks, walkways, and narrow slab pours. Estimating a driveway? Estimate ready-mix concrete and bag counts for a residential driveway slab.
Check footing volume Estimate concrete yards and bags for continuous strip footings. Estimate wall concrete Estimate concrete yards for wall pours using length, height, and thickness. Calculate stair concrete Estimate concrete for solid stair pours using width, tread depth, riser height, and step count. Round columns and piers Calculate concrete volume for round columns and piers.
Need bag counts instead? Convert slab dimensions into 40 lb, 60 lb, and 80 lb concrete bag counts. Convert to cubic yards Calculate cubic yards of concrete from project dimensions. Post Hole Concrete Calculator Calculate concrete bags for fence post holes, deck posts, and footings.

FAQ

Concrete estimating questions

How do I calculate cubic feet of concrete?

Multiply length by width by thickness in feet. Convert inches to feet before multiplying; for example, 4 inches equals 0.333 feet.

How many cubic feet are in a cubic yard?

There are 27 cubic feet in one cubic yard.

Why use cubic feet for bag concrete?

Bag yield is usually listed in cubic feet, so cubic feet make it easier to compare required volume against bag yield.

Should I convert each section separately?

For fewer rounding errors, add all section volumes in cubic feet first, then convert the total to yards or bags.