BC BuilderCalc

concrete

Concrete Yards Calculator

Calculate cubic yards of concrete from project dimensions.

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.
Example9 x 9 ft slab x 4 in = about 1.00 yd³ before waste

Cubic yards are the ready-mix ordering unit. Add waste before asking for a quote.

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

SSR formula reference

Concrete Yards 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

Yard planning

Concrete Yards Calculator planning notes

Cubic yards are the ordering unit for ready-mix concrete. The key is converting field dimensions into cubic feet first, then dividing by 27.

Round for ordering, not for math

Keep the exact calculation visible, then round the order after adding waste. Rounding too early can hide real volume on small pours.

Separate irregular sections

An L-shaped slab or flared driveway should be split into simpler shapes before converting to yards.

How to use it

Keep the estimate tied to field measurements

01

Calculate cubic feet

Convert all dimensions to feet and multiply length by width by thickness.

02

Convert to yards

Divide cubic feet by 27 to get cubic yards, then add your waste allowance.

03

Confirm order minimums

Small yardage can trigger delivery or short-load fees, so confirm supplier minimums.

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. Work in cubic feet Calculate concrete cubic feet, cubic yards, and cubic meters. Post Hole Concrete Calculator Calculate concrete bags for fence post holes, deck posts, and footings.

FAQ

Concrete estimating questions

How do I convert cubic feet to cubic yards?

Divide cubic feet by 27. One cubic yard contains 27 cubic feet.

Should I order the exact cubic yards shown?

Usually no. Use the exact number to understand the math, then add a waste allowance for field conditions before ordering.

Why is concrete sold by the cubic yard?

Ready-mix suppliers batch and deliver concrete by volume, and the cubic yard is the standard ordering unit in the United States.

Can I add multiple shapes together?

Yes. Split irregular projects into simpler sections, calculate each volume, then add the cubic-yard totals before applying waste.