Topsoil calculator

How deep should topsoil be?

At least 4–6 inches for a new lawn and 6–8 inches (150–200 mm) for borders.

The topsoil depth guide explains each case, including how much compost to mix in. For raised beds, the raised bed soil calculator handles several beds and bag sizes at once.

Topsoil for a new lawn

Penn State specifies at least 4–6 inches of good topsoil for a new lawn and stresses that this is the firmed or settled depth.^[1] They also suggest mixing about 2 inches of the new topsoil into the upper 2–3 inches of subsoil, and tilling at least 4 inches deep.^[1]

Settling: why loose topsoil goes further on paper than in the ground

Topsoil arrives loose and settles once it is spread, watered and walked on. Penn State gives its lawn depth as a settled depth,^[1] so spread a little more than the target. For a sense of scale, the US Army's earthmoving tables give loam a loose-to-compacted factor of 0.72,^[5] though that is for machine compaction, much firmer than a lawn. A UK producer adds that laying too much topsoil can lead to settling over time.^[2] There is no single published settling allowance for garden topsoil, so use the "Add extra" option to add a margin you are comfortable with.

How much does a yard of topsoil weigh?

About 1,900–2,200 lb dry and 2,800–3,200 lb wet per loose cubic yard; water adds a lot. US Army tables give a loose cubic yard of loam or topsoil as 1,900–2,200 lb dry and 2,800–3,200 lb wet.^[5] That is 0.95–1.1 US tons dry against 1.4–1.6 wet. A UK producer gives 1 tonne of its standard topsoil as about 0.67 m³, or roughly 1.5 tonnes per cubic meter,^[2] between the two. Choose dry or wet topsoil in the calculator to see the weight range. Once the topsoil is down, the grass seed calculator gives the seed for the area. For filling holes and low spots below the topsoil layer, the dirt calculator adds compaction factors for loam and clay.

Bags and bulk bags

Bagged garden soil comes in sizes such as 0.75, 1, 1.5 and 2 cu ft.^[6] A cubic yard is 36 bags of 0.75 cu ft or 18 bags of 1.5 cu ft. In the UK, one producer's topsoil bulk bags hold about 0.5 m³ and cover up to 10 m² at 50 mm, with a larger 0.75 m³ bag covering up to 15 m².^[7]

Bags or bulk topsoil?

A cubic yard of topsoil is 27 bags of 1 cu ft or 18 bags of 1.5 cu ft, so bags suit small beds and bulk suits whole lawns.

Common topsoil mistakes

The most common mistake is ordering for the loose depth: Penn State's 4–6 inches for a new lawn is the firmed or settled depth, so spread a little more.^[1]

• Laying topsoil as a separate layer. Mix about 2 inches of it into the upper 2–3 inches of subsoil.^[1]
• Going too thin for a new lawn. The minimum is 4–6 inches, settled.^[1]
• Buying by weight after rain. Wet loam weighs 2,800–3,200 lb per cubic yard against 1,900–2,200 dry, so a ton buys less soil.^[5]
• Top-dressing too heavily. Keep compost top-dressing to about ¼ inch per application.^[4]

How much is a ton of topsoil?

One US ton of loose topsoil is about 0.91–1.05 cubic yards when dry, but only 0.62–0.71 cubic yards when wet, because water adds weight.^[5]

A metric tonne is about 10% more than a US ton; a UK producer gives 1 tonne of its standard topsoil as about 0.67 m³.^[2]

How much does a yard of topsoil cost?

A yard of topsoil costs your supplier's price per cubic yard, plus delivery; if they sell by the ton, a dry yard weighs about 0.95–1.1 US tons and a wet one 1.4–1.6.^[5] Enter your quotes in the price fields to see the total by the yard, by the ton and in bags.

Example: patching low spots in a lawn

Three low patches of about 6 × 4 ft each, filled 2 inches deep, total 72 sq ft × 2 ÷ 324 = 0.44 cubic yards, or 12 cubic feet: 12 bags of 1 cu ft or 8 bags of 1.5 cu ft. Enter each patch as its own area, or one known area of 72 sq ft.