Bulk Estimator

Compost Calculator — cubic yards, tons and bags

Enter your area and the depth you want to apply, and get cubic yards, tons and bags — using the compost industry's own published bulk density figures.

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Advanced: density, price and truck capacity
lb/ft³

Leave blank to use our sourced range:

Compost is sold by the cubic yard in bulk and by the bag for small jobs, but the application rate that matters is a depth spread over an area — a quarter inch to top-dress a lawn, two or three inches to amend a bed. This calculator does that conversion.

The bulk density comes from the US Composting Council's Field Guide to Compost Use, which gives 700 to 1,200 lb/yd³ as the typical range for municipal composts and 800 to 1,000 lb/yd³ as preferred. That is a wide band, and it is wide for a real reason: the same document records moisture contents of 30 to 60%, and water is heavy.

Because compost shrinks as it matures, we default the waste allowance higher than for aggregate. If you are filling a bed to a finished depth, buying to the finished volume will leave you short.

A worked example you can check by hand

A 20 ft × 10 ft area at 2 in deep, with a 5% waste allowance:

Area200 ft² (20 ft × 10 ft)
Depth2 in = 0.1667 ft
Volume (before waste)33.3333 ft³
Waste allowance5%
Volume (with waste)35 ft³ = 1.2963 yd³
Density used25.9 / 33.3 / 44.4 lb/ft³ (low / typical / high)
Weight (low)907 lb = 0.4533 short tons
Weight (typical)1,166 lb = 0.5828 short tons
Weight (high)1,554 lb = 0.777 short tons

How we calculate this — and every number we used

We do not use a hidden "magic number". Here is the entire calculation:

  1. volume = area × depth
  2. volume_with_waste = volume × (1 + waste%)
  3. weight = volume_with_waste × density

Why a range, not one number? Bulk material density changes with moisture, gradation and compaction. Publishing a single figure would be falsely precise, so we publish the range our sources support — and we show you exactly where each number comes from.

Why we state the state. This material is only published at one placement state, so there is nothing to choose — but we say which one it is, because loose and compacted material differ by 27–60% in volume and most calculators never tell you which they used.

Compost — loose, as delivered (moisture included)

Stateloose (stockpiled)
Moisture basisas-is, 30-60% moisture content typical
Density (low / typical / high) 25.9 / 33.3 / 44.4 lb/ft³ = 0.35 / 0.45 / 0.6 short ton/yd³
Last reviewed2026-09-13

How we chose the typical value. The US Composting Council gives 700-1,200 lb/yd³ as the typical range for municipal composts, with 800-1,000 lb/yd³ preferred. Dividing by 27 gives 25.9-44.4 lb/ft³; we set the typical at 900 lb/yd³ (33.3 lb/ft³), the middle of the preferred band.

Single-source constant. We could only retrieve one authoritative published figure for this material, so the range may understate real-world variation. Confirm the figure with your supplier before ordering.

Limits of this constant

  • Moisture content drives compost density: the same source gives 30-60% moisture, and wetter compost is substantially heavier per cubic yard.
  • Screened and unscreened compost, and compost blended with sand or soil, all differ. Ask your supplier for the bulk density of the actual product.
  • Compost also continues to settle and shrink as it matures, so buy slightly more than the finished volume you want.

Source

Assumptions and limits

This calculator is only valid under these assumptions. If any of them do not match your project, treat the result as a rough guide and get a quote from your supplier.

Frequently asked questions

How much does a cubic yard of compost weigh?

Between about 0.35 and 0.6 short tons per cubic yard, with about 0.45 as a working figure. The US Composting Council gives 700–1,200 lb/yd³, and prefers 800–1,000.

How much compost to top-dress a lawn?

A quarter inch is a normal light top dressing and half an inch is a heavy one. For 1,000 square feet at a quarter inch you need about 0.8 cubic yards — under a yard, so bags may be more practical than a delivery.

Why is the weight range so wide?

Because compost density is driven by moisture and by how coarse the material is. The industry's own field guide records 30–60% moisture content across products. If you are buying by the ton rather than the yard, ask your supplier for the bulk density of the actual batch.

Should I order extra compost?

Yes. Compost continues to settle and mineralise after delivery, so the finished depth is less than what you spread. We default to a 10% allowance; use 15% if you are filling to a specific finished level.

Is this a fertiliser recommendation?

No. This calculator only works out how much material to buy. Nutrient rates depend on a soil test and on what you are growing, which is an agronomic question rather than a volume calculation.

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