How it works
Three numbers, and an answer in the units your landscape supplier actually quotes.
Measure the bed
Length and width in feet. Round beds: multiply radius by radius by 3.14.
Set the depth
4 to 6 inches for a new garden bed, 2 to 3 inches for topdressing an existing lawn.
Get yards, bags and tons
Bulk is sold by the yard or ton; bags by the cubic foot. We give you all three.
When to stop buying bags
Topsoil volume is the same calculation as any other loose material: length times width times depth, with the depth converted from inches to feet, then divided by 27 to get cubic yards. A 20 by 10 foot bed filled 6 inches deep comes to 100 cubic feet, which is 3.7 cubic yards.
The number worth paying attention to is the bag count. A 40 lb bag of topsoil holds about 0.75 cubic feet, so that same bed needs 134 bags. At typical prices that is several times the cost of a bulk delivery, and it means loading and unloading 134 bags by hand. The crossover point is around one cubic yard: below that, bags are more convenient; above it, order bulk and have it dumped.
Weight matters if you are hauling it yourself. Screened topsoil runs roughly 1.1 short tons per cubic yard when dry, so 3.7 yards is about 4 tons — well beyond what a half-ton pickup should carry in one trip. Wet soil is considerably heavier, and suppliers sell by weight after rain just as they do before it.
For depth: a new planting bed wants 4 to 6 inches of good soil, vegetable beds want 8 to 12, and topdressing an existing lawn takes only a quarter to half an inch at a time. Filling deeper than the plants need is the most common way people overspend here.
Frequently asked questions
How many bags of topsoil in a cubic yard?
About 36 bags at 0.75 cubic feet each, which is the standard 40 lb bag. Bags labelled 1 cubic foot come to 27 per yard.
How much does a yard of topsoil weigh?
Roughly 1.1 short tons, or about 2,200 lb, when the soil is dry and screened. After heavy rain it can exceed 3,000 lb.
How deep should topsoil be for a new bed?
4 to 6 inches for flowers and shrubs, and 8 to 12 inches for vegetables. Lawns being topdressed need only a quarter to half an inch per pass.
Is bulk topsoil cheaper than bags?
Almost always, above about one cubic yard. Below that the delivery fee usually outweighs the saving.
More material calculators
Estimates are for planning only. Confirm quantities with your supplier before ordering.