Compost Calculator
Enter your area and depth — get cubic yards, bags, weight, and bagged-vs-bulk cost for compost in seconds.
A typical loose density — weight varies with moisture and mix. Suppliers differ, so pick Custom to enter yours.
Add 10% extra for settling & uneven ground (handy for beds and fill)
Bags are convenient for small areas; bulk by the cubic yard usually wins once you need more than about three-quarters of a yard, delivery included. Enter your local prices — we'll show which wins and by how much.
How much compost you need.
Compost is decomposed organic matter used to enrich soil, top-dress lawns, and feed beds. It is much lighter than soil — about half the weight per cubic yard — but it is still bought by volume, so the job starts with your area and depth. The calculator returns cubic yards, the number of bags at four sizes, and an approximate weight.
A thin layer does a lot: 1 to 2 inches worked into a bed, or about a quarter to half an inch as a lawn top-dressing. Spreading it much thicker wastes material, so pick a shallow depth and let the calculator size the order.
Volume, depth, and how much to buy.
Every estimate starts from volume: area multiplied by depth. Measure length and width in feet, pick a depth, and the calculator works out cubic feet, then divides by 27 for cubic yards. If your depth is in inches it divides by 12 first, and you can enter dimensions in feet, inches, or yards.
Depth is where most over- and under-buying happens, because it is small but multiplies across the whole area. A 2-inch topping over 200 square feet is about 1.2 cubic yards; the same area at 6 inches is more than 3.5. Choose the shallowest depth that does the job, then round up to what your supplier will sell.
Why soil is sold by the yard.
Bulk soil is priced by the cubic yard, but weight still matters for hauling. A cubic yard of typical screened soil or topsoil weighs roughly 2,240 lbs — about 1.12 tons. Fill dirt is heavier at around 2,700 lbs a yard, while compost is much lighter at roughly 1,000 lbs. The calculator turns your volume into a weight using the density for the type you pick, and you can enter a custom figure.
Moisture is the big variable: wet soil weighs noticeably more than the same volume dry, and packing it down adds weight per yard too. Treat the tonnage as a planning number, round up, and confirm the density with your supplier before a bulk order or before loading a trailer.
Bags or bulk — and how much.
Bagged soil and compost are easy to handle and make sense for a bed or two, a few containers, or a small top-dressing. Bag sizes vary, so the calculator counts four common ones — 0.75, 1, 1.5, and 2 cubic feet. A cubic yard is 27 cubic feet, so it takes 36 of the smallest bags or 14 of the largest to equal one yard. Once a project needs more than about three-quarters of a yard, bulk delivery is usually cheaper even after the delivery fee.
Whichever way you buy, order a little extra. Soil settles, works into uneven ground, and compacts, so turning on the 10% overage option or rounding each part-yard up keeps you from coming up short.
How far a cubic yard goes.
Area that one cubic yard covers at common depths. One cubic yard is 27 cubic feet, so coverage is 324 ÷ depth in inches.
| Depth | One cubic yard covers | Good for |
|---|---|---|
| 1 inch | 324 sq ft | Light top-dressing |
| 2 inches | 162 sq ft | Lawn topsoil, thin layer |
| 3 inches | 108 sq ft | Topsoil over bare ground |
| 4 inches | 81 sq ft | Bed prep, regrading |
| 6 inches | 54 sq ft | New beds, deeper fill |
| 12 inches | 27 sq ft | Raised beds, deep fill |
Coverage is volume ÷ depth: a cubic yard spreads over 324 ÷ depth (in.) square feet. Typical soil weighs about 2,240 lbs per cubic yard, fill dirt about 2,700, and compost about 1,000 — wetter material weighs more.
Frequently asked questions.
How much does a yard of soil weigh?
A cubic yard of typical screened soil or topsoil weighs about 2,240 lbs, or roughly 1.12 tons. Fill dirt is heavier at around 2,700 lbs a yard, and compost is much lighter at about 1,000 lbs. Wet or compacted material weighs more, so treat these as planning figures.
How many bags of soil are in a cubic yard?
It depends on the bag size. A cubic yard is 27 cubic feet, so it takes 36 bags of 0.75 cu ft, 27 bags of 1 cu ft, 18 bags of 1.5 cu ft, or 14 bags of 2 cu ft. The calculator shows all four counts so you can compare.
How deep should soil or topsoil be?
It depends on the job. A light top-dressing is 1 to 2 inches, fresh topsoil over bare ground is usually 2 to 4 inches, and new garden beds want 6 to 12 inches so roots can spread. Compost worked into a bed is about 1 to 2 inches. Enter your depth above and the calculator sizes the order.
What is the difference between topsoil and fill dirt?
Topsoil is the fertile top layer of soil, screened for planting lawns and beds. Fill dirt is subsoil from below that layer — denser, with more clay and rock and little organic matter — used to raise and level ground, not to plant in. Fill dirt is cheaper and heavier per yard. Pick the soil type above to match your job.
How do I convert cubic yards of soil to tons?
Multiply cubic yards by the material's weight per yard in tons: about 1.12 for screened soil and topsoil, about 1.35 for fill dirt, and about 0.5 for compost. The calculator does this for you and lets you adjust the density for wet or unusual material.
Methodology & sources
Volume is standard geometry: the area is multiplied by the depth for cubic feet, divided by 27 for cubic yards, and multiplied by 0.0283168466 for cubic meters. Weight is cubic feet × density (lb/ft³) ÷ 2,000 for US tons, and each bag count is cubic feet ÷ the bag size, rounded up. All arithmetic was verified with Python's Decimal to avoid floating-point drift.
Density references (.gov / .edu):
- Penn State Extension — soil bulk density. 1.33 g/cm³ (about 83 lb/ft³, ~2,240 lb/yd³) is the standard value used for mineral soil, close to a silt loam; USDA NRCS (below) gives the same figure for a medium-textured soil — link
- USDA Natural Resources Conservation Service — Soil Quality Indicators: Bulk Density. Denser, clay- and rock-rich fill sits nearer 1.6 g/cm³ (about 100 lb/ft³, ~2,700 lb/yd³) — link
- University of New Hampshire Extension & Oregon State University Extension (EM 9217) — compost bulk density (~1,000 lb/yd³ for screened compost) — link
Defaults are typical loose values: ~82.9 lb/ft³ for screened soil, topsoil, and dirt; ~100 lb/ft³ for fill dirt; and ~37 lb/ft³ for compost. Moisture and mix move these, and supplier weights vary, so the density field is editable — confirm before a bulk order.
Unit conversions (27 cu ft = 1 cu yd; 1 cu ft = 0.0283168466 m³) are exact definitions. Last methodology review: June 2026.
Independence: Sources are cited for reference only. The universities, agencies and retailers named on this page do not sponsor or endorse MaterialCalcs, and we are not affiliated with them. Retail prices were checked by hand and vary by store and region.