Topsoil Calculator

How the topsoil calculator works

Topsoil is ordered by volume, but it is delivered by weight or in bags, so a single job usually needs three different numbers. This calculator produces all of them from one set of measurements.

1. Pick US units or Metric units. The unit system decides whether results are given in cubic yards and tons or in cubic metres and tonnes.
2. Enter the width, length and depth of the area. Each measurement has its own unit menu, so you can type a bed in feet and its depth in inches without converting anything.
3. Choose In Bags or In Bulk. For bags, type the bag size and choose the unit printed on the label (cubic feet, cubic yards, cubic metres, pounds, kilograms or litres).
4. Optionally add a price. For bags it is the price of one bag; for bulk it is the price per ton (US units) or per tonne (metric units).

The results show the volume of soil needed and its estimated weight. With a bag size you also get the number of bags, and with a price you get the total cost and the effective price per ton or tonne.

The formulas behind the numbers

volume = width × length × depthAll three measurements must be in the same unit before multiplying. The calculator converts them for you.

cubic yards = cubic feet ÷ 27

weight = volume × density

bags = volume ÷ bag volume (or total weight ÷ bag weight)

cost = bags × price per bag (or tons × price per ton)

The weight estimate uses a fixed density of 1,600 kg per cubic metre, which is about 99.9 lb per cubic foot or 2,697 lb (1.35 short tons) per cubic yard. That is a reasonable middle value for moist garden loam. If your supplier quotes a different weight per yard, scale the weight result by the ratio of the two figures.

The number of bags is not rounded, so you may see something like 17.78. Round it up yourself, because shops sell whole bags only.

Worked example: filling a raised bed

A raised bed measures 8 ft by 4 ft and will be filled 10 inches deep. Bags of topsoil hold 1.5 cubic feet and cost $5.25 each.

• Volume: 8 × 4 × (10 ÷ 12) = 26.667 ft³, which is 26.667 ÷ 27 = 0.988 cubic yards.
• Weight: 26.667 ft³ × 99.9 lb/ft³ ≈ 2,664 lb, or 1.33 tons.
• Bags: 26.667 ÷ 1.5 = 17.78, so buy 18 bags.
• Cost: the calculator prices the fractional 17.78 bags at $93.33. Eighteen whole bags cost 18 × $5.25 = $94.50.

Fresh soil settles as it is watered. Adding 10% to the volume (29.3 ft³) lifts the bag count to 19.56, so ordering 20 bags leaves a small margin to top up the bed.

How deep should topsoil be?

The right depth depends on the job. These are common rules of thumb for home projects; local extension services and landscape professionals may recommend different figures for your climate and subsoil.

Depth has the largest effect on the total because it multiplies everything else. Doubling the depth doubles the soil, so measure it instead of guessing.

Cubic yards by area and depth

For a quick estimate without a calculator, find the area in square feet and read across for the depth you plan to use. Values are cubic yards, rounded to two decimals.

Topsoil weight, tons and tonnes

Soil weight varies a lot. Dry, sandy or organic mixes can be well under 1,300 kg per cubic metre, while wet or compacted clay-rich soil can pass 1,700 kg per cubic metre. A rain-soaked pile weighs noticeably more than the same pile in dry weather, so treat the weight result as an estimate for planning trucks and trailers.

Be careful with the word ton. A short ton (US) is 2,000 lb, or 907.18 kg. A metric tonne is 1,000 kg, or about 2,204.6 lb. A long ton (UK) is 2,240 lb. This tool reports short tons in US mode and tonnes in metric mode, and the price field follows the same unit.

Check whether your supplier prices by the cubic yard, the ton or the truckload before comparing quotes. Converting everything to cubic yards with the 1,600 kg/m³ density above gives a fair like-for-like comparison.

Bags or bulk delivery?

Bags are convenient for small beds, containers and areas a truck cannot reach. Bulk delivery is usually cheaper per unit for anything over about a cubic yard, but you need somewhere to tip it and a way to move it to the site.

To compare, convert bags to cubic yards: one cubic yard is 27 cubic feet, so a 1.5 cu ft bag means 18 bags per yard, a 2 cu ft bag means 13.5 bags (buy 14), a 1 cu ft bag means 27 bags and a 0.75 cu ft bag means 36 bags. Multiply by the bag price and set it against the bulk price per yard plus the delivery fee.

Common mistakes

• Mixing units. Typing a depth of 6 while the menu says feet instead of inches multiplies the answer by twelve.
• Forgetting settling. Loose soil compacts by roughly a tenth as it is watered and walked on; add a margin.
• Rounding bags down. A bag count of 17.78 means 18, never 17.
• Treating a ton as a tonne. The two differ by about 10%, which matters for delivery weight limits.
• Ignoring the surface. Mounded or sloping ground needs a larger average depth than the edge measurement suggests.

For other landscaping materials, see the mulch calculator, the gravel calculator and the sand calculator. Flat-sided concrete work has its own concrete calculator, and volume-of-box formulas cover any rectangular space.