how many yards of concrete do i need

You can figure out how many yards of concrete you need with one simple formula, plus a small safety margin.

Basic formula (most projects)

Concrete is ordered in cubic yards.
First convert your measurements to feet and then use:

Cubic yards=Length (ft)×Width (ft)×Thickness (ft)27\text{Cubic yards}=\frac{\text{Length (ft)}\times \text{Width (ft)}\times \text{Thickness (ft)}}{27}Cubic yards=27Length (ft)×Width (ft)×Thickness (ft)

1 cubic yard = 27 cubic feet.

If thickness is in inches, convert to feet: thickness in feet = thickness in inches ÷ 12.

Example: small patio slab

Say your patio is:

Length: 10 ft
Width: 10 ft
Thickness: 4 in (that’s 4÷12=0.334÷12=0.334÷12=0.33 ft)

Steps:

Compute volume in cubic feet:
- 10×10×0.33≈3310×10×0.33≈3310×10×0.33≈33 cubic feet.

Convert to yards:
- 33÷27≈1.2233÷27≈1.2233÷27≈1.22 cubic yards.

You’d order about 1.25 cubic yards to be safe (always round up a bit).

Quick reference examples

These are rough estimates for typical thicknesses.

10 ft × 10 ft slab, 4 in thick → about 1.2–1.3 yd³.

4 ft × 10 ft sidewalk, 4 in thick → about 0.5 yd³.

10 ft × 20 ft driveway, 6 in thick → about 3.7 yd³.

Pro tips for your order

Add 5–10% extra to cover spillage, uneven subgrade, and minor measuring errors.

Break odd or curved shapes into rectangles, calculate each piece, then add them together.

For big or complex jobs (stairs, walls, footings), calculate each element separately or use an online concrete calculator and then still round up slightly.

“How many yards do I need?” checklist

Before you calculate, make sure you have:

Project type (slab, sidewalk, driveway, footing, wall, etc.).
Length and width measured in feet (or converted to feet).
Thickness in inches, converted to feet.
A small overage factor (add 0.1–0.25 yd³ on small pours, or 5–10% on larger pours).

If you tell me your length, width, and thickness , I can calculate the exact cubic yards you should order (with a suggested safety margin) for your specific project.