How much soil do you need?
Soil is a volume job. Multiply the length by the width by the depth, and you have the cubic measure of what to order. The only trap is mixing units: if your area is in feet and your depth is in inches, divide the depth by 12 first. A 20 by 10 foot bed filled 4 inches deep is 20 x 10 x (4/12) = 66.7 cubic feet, which is about 2.5 cubic yards or 1.9 cubic metres.
The calculator also adds an allowance for settling, set to 10 percent by default. Loose soil drops as it gets watered and walked on, and you will always be glad you ordered a bit extra. If you are topping up a bed that has already settled, you can lower it to 5 percent.
How deep should the soil be?
It depends on what you are growing and what is underneath. These are common starting points.
| Project | Typical depth |
|---|---|
| New lawn over decent existing soil | 100 to 150 mm (4 to 6") |
| Lawn on compacted clay or fill | 150 to 200 mm (6 to 8") |
| Perennial and flower beds | 200 to 300 mm (8 to 12") |
| Raised vegetable beds | 300 to 450 mm (12 to 18") |
| Top-dressing an existing lawn | 6 to 12 mm (1/4 to 1/2") |
Much of southern Ontario, the Prairies and the Lower Mainland sit on heavy clay or builder fill, which is why many new lawns get 150 mm or more of topsoil before sod goes down. If you are laying turf, our sod calculator sizes the rolls, and the soil depth should leave the sod surface level with walkways and driveways.
Cubic yards, cubic metres and tonnes
Canadian suppliers are not consistent. Garden centres and landscape yards often quote soil by the cubic yard, bulk suppliers sometimes sell by the tonne, and engineers and municipalities work in cubic metres. One cubic metre is 1.308 cubic yards. A cubic yard of moist topsoil typically weighs close to a tonne, and screened topsoil is usually somewhere between 1 and 1.4 tonnes per cubic metre depending on moisture. A load can therefore look small in volume but still be a heavy haul for a half-ton pickup. Check your truck or trailer rating before you load.
Bagged soil or bulk delivery?
Bags are convenient for small jobs. A typical 28 litre bag covers about 0.028 cubic metres, so you need around 36 bags for one cubic metre. Once you pass about half a cubic metre, bulk delivery is usually cheaper and creates far less plastic waste. Ask the supplier what the minimum delivery is and whether the price includes the truck.
Topsoil, garden mix and triple mix
These are not interchangeable. Topsoil is screened native soil, usually the cheapest, and works for levelling and lawns. Garden soil and triple mix blend topsoil with compost and sometimes peat or sand. They hold nutrients and drain better, which suits raised beds and planters, but are overkill under sod. For a first-year vegetable bed, many gardeners use a mix of topsoil and compost and top it up each spring. If your area has drainage problems, a layer of gravel or crushed stone underneath may do more good than more soil on top.
Tips before you order
Measure irregular beds by splitting them into rectangles and adding the volumes. For a circular bed, use 3.14 x radius x radius x depth. Pile the delivery on a tarp near the work area, and keep it out of the way of storm drains. Spread it in the spring or early fall when the ground is workable, and avoid working soil that is waterlogged, which compacts it.
Frequently asked questions
How do I calculate how much topsoil I need?
Multiply length by width by depth, using the same units, then convert to cubic yards or cubic metres. Add about 10 percent for settling.
How many cubic yards of soil do I need for a 10 by 20 foot garden?
At 4 inches deep you need about 2.5 cubic yards, or about 2.7 yards with 10 percent extra for settling.
How much does a cubic yard of topsoil weigh?
Roughly a tonne when moist, though it varies with moisture and how much organic material is in the mix.
How many bags of soil make a cubic metre?
About 36 bags of 28 litres, since one cubic metre is 1,000 litres.
How deep should topsoil be for a lawn?
Plan on 100 to 150 mm (4 to 6 inches). Go deeper if you are over clay, fill or compacted ground.
Is topsoil the same as garden soil?
No. Topsoil is screened native soil. Garden soil and triple mix include compost or other additions and are better for beds and planters.
Related calculators
Estimates only. See our disclaimer and how we calculate.