Topsoil calculator

Topsoil by area and finished depth. Cubic yards or cubic metres, a settling allowance so the order compacts back to grade, the count of 0.75 ft³ bags, and the bag-vs-bulk break-even most calculators leave you to work out at the register.

01 How the math works

Topsoil volume is area times finished depth, with the depth converted to the same unit as the area. For a rectangular area that is length × width; for a round area it is π × radius². Multiply by the depth in feet and you have cubic feet; divide by 27 for cubic yards.

That volume is the finished grade — the soil after it has settled. Loose topsoil, fresh off the pile or out of the bag, holds more air than the same soil once it is spread, watered, and left, so you buy more loose material than the finished volume to end up level. The calculator applies two separate multipliers on top of the geometric volume: a settling allowance for that compaction, and an ordinary waste factor for spillage and uneven subgrade. Both are editable.

Bags are the order volume divided by the bag size, rounded up to the whole bag. The standard big-box topsoil bag is 0.75 ft³; some lines are 1.0 ft³ or 1.5 ft³, so the field is editable. Bulk topsoil is sold by the cubic yard, which is 27 ft³ — the same 36 of those 0.75 ft³ bags. That number is the entire bag-vs-bulk comparison, and 36 is a big enough multiplier that topsoil is the material where it almost never comes out close.

02 Worked example

Take a low 20 ft × 20 ft (6.10 m × 6.10 m) patch of lawn you want to build up 3 in (76 mm) to level it before reseeding.

Area is 400 ft² (37.16 m²). Finished volume: 400 × 0.25 ft = 100 ft³ = 3.70 yd³ (2.83 m³). Apply a 15% settling allowance and a 10% waste factor — that is 1.15 × 1.10 = 1.265, so the loose order is 126.5 ft³ = 4.69 yd³.

Bagged, at 0.75 ft³ per bag, that is 169 bags. Bulk rounds 4.69 yd³ up to the yard's half-yard step: 5.0 yd³. One cubic yard of topsoil is 36 of those bags, so 169 bags is the entire reason nobody fills a ground job out of sacks. At the NRCS figure for medium-textured soil, that finished 3.70 yd³ weighs about 8,300 lb (3,770 kg) — just over four US tons, and a cubic yard on its own is already more than most half-ton pickups are rated to carry.

03 When this calculator is wrong

The volume is exact arithmetic. What it does not know is how much your soil will settle, how heavy the load is, or the shape of your real area — and those are where the order and the delivery go off.

• The settling allowance scales with the job, and the 15% default is a middle value, not a law. Loose screened mineral topsoil used as fill settles roughly 10–15% over the first season as it is watered and compacts. Clay-heavy or compost-rich mixes drop more — 20% or past it — because they hold more air and organic matter that squeezes out. Sandy soils settle less. This is the waste-factor principle from across this site applied to soil: the allowance should match the job, not stay pinned at one number (opinions.md O1). The exception is top-dressing an existing lawn with under about 1 in — there is no real fill to settle, so set the allowance to zero and the extra soil just over-orders.
• It assumes you are filling to a finished grade. If you are only raking a thin dressing over existing turf, enter the thin depth you are adding, not a target you imagine. Entering a full build-up depth over ground that is already close over-orders by yards, and a yard of topsoil you do not need is a pile in the driveway, not a returnable bag.
• Weight is an estimate, and topsoil is heavy. The weight shown uses the USDA NRCS figure for an ideal medium-textured soil — about 1.33 g/cm³, or 2,240 lb/yd³ (1,017 kg/yd³), roughly 1.1 US tons per cubic yard. Real weight moves with moisture: dry screened soil is lighter, soil saturated after rain is heavier. Use the number to decide delivery versus pickup, not to fill a truck to the pound. A single cubic yard already exceeds the rated payload of most half-ton pickups, so a full yard is a delivery.
• It treats the area as a clean rectangle or circle. Real grading areas wrap around beds, walks, and tree rings. Measuring the bounding box over-orders; breaking an irregular area into rectangles and quarter-circles and adding them is closer. The round mode is for a circular low spot or a tree ring, not an L-shaped yard.

04 What to do with the result

Compute the finished volume, apply the settling allowance and the waste factor, and round up — to the whole bag for bagged, or to the yard's increment for bulk. Rounding up is the right call on every material order, because a second delivery for one short yard costs far more than the yard. For topsoil the split in that rule is sharp: unopened bags are returnable at most garden centers, but a bulk pile dumped on your driveway is not, so round bulk up by the smallest scoop the yard sells rather than a full extra yard.

To decide between bags and bulk, use the break-even the calculator prints: one cubic yard is 36 of the 0.75 ft³ bags. Multiply the bag price by 36 and compare it to the yard's bulk price per cubic yard, delivery included. Because that multiplier is so high — and because a cubic yard weighs north of a ton — topsoil crosses over to bulk at a far smaller job than mulch does. Bags earn their keep for a planter, a few low spots, or anywhere a truck cannot reach; past roughly half a yard, bulk almost always wins.

05 Common questions

How much topsoil do I need?

Multiply the area's length by its width for square footage, then by the finished depth in feet (3 in is 0.25 ft) for cubic feet, and divide by 27 for cubic yards. Then add a settling allowance so the loose soil compacts back to grade. A 20 × 20 ft patch built up 3 in is 100 ft³ finished, about 4.69 yd³ to order with a 15% settling allowance and 10% waste.

How many bags of topsoil are in a cubic yard?

A cubic yard is 27 ft³, so it holds 36 of the standard 0.75 ft³ bags, 27 of the 1.0 ft³ bags, or 18 of the 1.5 ft³ bags. Read the bag — volume varies by product line.

How much does a cubic yard of topsoil weigh?

At the USDA NRCS figure for medium-textured soil (1.33 g/cm³), about 2,240 lb (1,017 kg) — roughly 1.1 US tons. Dry screened soil is lighter; soil saturated after rain is heavier. A full cubic yard is over the rated payload of most half-ton pickups, so plan on delivery.

How much area does a yard of topsoil cover?

Coverage is volume divided by depth. One cubic yard covers 324 ft² at 1 in, 162 ft² at 2 in, 108 ft² at 3 in, and 81 ft² at 4 in (30.10 / 15.05 / 10.03 / 7.53 m²). Oregon State University Extension quotes the same 162 ft² at 2 in. That is the finished depth — add the settling allowance to what you order.

Should I buy topsoil in bags or in bulk?

Bulk is cheaper per cubic yard for anything past about half a yard, and the gap is wide because one cubic yard is 36 × the 0.75 ft³ bag. Bulk wins when its price per cubic yard, delivery included, is below 36 times the price of one bag. Bags are for planters, a few low spots, or spots a truck cannot reach.