What this calculator does

Concrete is sold by the cubic metre or cubic yard, so the length, width and thickness must be turned into volume. This calculator does it for you and adds 10% extra for uneven ground and spillage.

How to use it

1. Measure the length and width of the slab, driveway, steps or walkway.
2. Enter the thickness. A walkway or patio is usually 4 in, a driveway often 4 to 6 in.
3. Use the result to order bags for a small job or a truck load for a bigger one.

Why it matters

Ordering too little concrete is the costly mistake. A cold joint where a second truck arrives late can crack and weaken the slab, and a short load fee adds up. Ordering too much wastes money. In Ontario, exterior concrete must survive freeze and thaw, so ask the supplier for an air-entrained mix. The thickness and the stone base under it decide how well it lasts through winter.

Tips from the job site

• Compact a gravel base before pouring. Concrete on soft soil settles and cracks.
• Add extra for steps, thickened edges and footings.
• Check the weather. Pouring on frozen ground or in heavy rain damages the finish.

These results are estimates. We measure on site before we quote, and we confirm local rules with your city.