How many cubic yards are in a square foot?

A square foot alone is an area, not a volume, so there's no fixed conversion until you add a depth. Multiply your area in square feet by the depth in feet, then divide by 27 to get cubic yards. For example, 100 sq ft at 0.5 ft deep = 50 ft³ ÷ 27 ≈ 1.85 cubic yards.

How do I convert square feet to cubic yards for concrete?

Multiply the slab area in square feet by the slab thickness in feet to get cubic feet, then divide by 27. A 10 ft x 10 ft slab (100 sq ft) at 4 in (0.33 ft) thick needs 100 x 0.33 = 33 ft³, which is 33 / 27 ≈ 1.22 cubic yards before waste.

Do ready-mix suppliers charge extra for small orders in Canada?

Most Canadian ready-mix suppliers have a minimum load and add a short-load fee below it, which can add a meaningful amount to a small order. If your calculated volume is small, ask about that fee before you order.

Square Feet to Cubic Yards Calculator — Concrete & Fill Volume

Square Feet to Cubic Yards Calculator

Concrete, mulch and gravel are priced and delivered by the cubic yard, but you almost always start with a flat area in square feet and a depth in inches. This calculator does that conversion in one step: enter your area (or a length and width instead) plus the depth you're filling or pouring, and it multiplies the two to give you cubic yards — plus a waste-adjusted purchase volume and a material cost estimate.

How to Use This Calculator

Enter the length and width of the area, or switch to a single area figure if you already have square feet.
Enter the depth of the slab, fill or mulch layer, in inches or feet.
Set a waste allowance — 10% is the default, covering compaction and sub-grade irregularity.
Read off the volume, the waste-adjusted purchase volume to order, and the estimated material cost.

The Math Behind the Conversion

The formula is simple: volume = area x depth, with depth converted into the same linear unit as the area before multiplying, then divided by 27 to turn cubic feet into cubic yards (since 1 yd³ = 3 ft x 3 ft x 3 ft = 27 ft³). Worked example, this calculator's own default: a 9 ft x 6 ft area (54 sq ft) at a 0.5 ft (6 in) depth. Volume = 54 x 0.5 = 27 ft³, and 27 / 27 = 1 cubic yard exactly. Add a 10% waste allowance and you'd order 1.1 cubic yards.

Pro Tips

At a typical Canadian ready-mix concrete price of around CA$175 per cubic yard delivered, this calculator's own default (9 ft x 6 ft at 0.5 ft deep = 1 cubic yard, or 1.1 cubic yards with a 10% waste allowance) works out to roughly CA$192.50 in material, before any pump or finishing labor.

Depth is the field most often entered in the wrong unit — double-check inches vs. feet, since a slab poured 6 in deep is 0.5 ft, not 6 ft.
Ready-mix concrete is typically sold in quarter-yard increments with a minimum load — round your purchase volume up to that increment rather than down.