Compost Calculator
Find how much compost your beds or lawn need, in cubic yards and bags.
What you'll need to order
- finished compost
- screened topsoil
- mulch (to top off)
Prices vary by region and haul distance. Get quotes from at least two local suppliers.
How this calculator works
cubic yards = length × width × (depth ÷ 12) ÷ 27
Finished compost weighs about 33 lb per cubic foot, roughly 890 lb per cubic yard — far lighter than topsoil. That means a cubic yard is easy to move by wheelbarrow but bulky to store.
Worked example
With length 10 ft, width 10 ft, depth 2 in, this calculator returns 0.62 cu yd.
Compost needed by depth
Figures below assume length 10 ft × width 10 ft. Change any measurement in the calculator to get your own numbers.
| Depth | Compost needed (cu yd) | 1.5 cu ft bags (bags) | Approximate weight (tons) |
|---|---|---|---|
| 0.25 in | 0.08 | 1.39 | 0.03 |
| 0.5 in | 0.15 | 2.78 | 0.07 |
| 1 in | 0.31 | 5.56 | 0.14 |
| 2 in | 0.62 | 11.11 | 0.27 |
| 3 in | 0.93 | 16.67 | 0.41 |
| 4 in | 1.23 | 22.22 | 0.55 |
Per 100 square feet. Quarter to half an inch is a lawn topdressing; two to three inches is a bed amendment.
How much compost for beds, lawns and raised planters?
| Job | Size | Compost needed | Material cost |
|---|---|---|---|
| Topdressing a small lawn | 40 ft × 25 ft × 0.25 in | 0.77 cu yd | $23 – $54 |
| Vegetable bed amendment | 20 ft × 4 ft × 2 in | 0.49 cu yd | $15 – $35 |
| New planting bed | 30 ft × 6 ft × 3 in | 1.67 cu yd | $50 – $117 |
| Filling a raised bed blended with topsoil, not neat |
8 ft × 4 ft × 4 in | 0.40 cu yd | $12 – $28 |
| Topdressing a full lawn | 80 ft × 50 ft × 0.25 in | 3.09 cu yd | $93 – $216 |
Compost is an amendment, not a growing medium. Work it into the top few inches of existing soil rather than laying it as a separate layer.
Cost range uses $30–$70 per cubic yard for material only.
What does compost cost?
Material typically runs $30 to $70 per cubic yard. Bulk, delivered. Bagged compost works out near $150 per cubic yard, so anything over about a yard is worth ordering loose.
What moves the price:
- Source — municipal green waste compost is cheapest, mushroom and worm castings cost far more
- Whether it is screened and fully matured
- Delivery minimums, usually 3 yards
- Spring demand, which pushes prices up noticeably
Prices are US averages and move with fuel, season and haul distance. Always get two local quotes before budgeting.
Compost types and what each is for
| Type | Typical depth to apply (in) | Notes |
|---|---|---|
| Lawn topdressing | 0.25 | Fine screened; never smother the grass |
| Bed amendment | 2.00 | Worked into the top 6 inches |
| Mushroom compost | 2.00 | High salts; avoid on seedlings |
| Leaf mould | 3.00 | Slow release, excellent structure |
| Composted manure | 1.00 | High nitrogen; must be well aged |
| Worm castings | 0.25 | Concentrated; used sparingly |
Fresh or partly composted manure burns roots and can carry weed seed. If it still smells of manure rather than soil, it needs another season.
Frequently asked questions
How much compost do I need for a raised bed?
For a 4 by 8 ft bed, about 0.1 cubic yards at 1 inch worked in. If you are filling the bed, blend one part compost to two parts topsoil rather than using compost alone.
How much compost to topdress a lawn?
A quarter of an inch, which is 0.77 cubic yards per 1,000 square feet. Anything thicker smothers the grass rather than feeding it.
When should I apply compost?
Autumn for beds, so it works into the soil over winter. For lawns, topdress right after core aeration in early autumn — the holes carry it down to the root zone.
How much compost do I need for a garden bed?
Two to three inches worked into the top 6 to 8 inches of soil is the standard amendment rate. A 20 by 4 ft bed at 2 inches deep needs about half a cubic yard, or nine 1.5 cu ft bags.
How many bags of compost make a cubic yard?
A cubic yard is 27 cubic feet, so 18 bags of 1.5 cu ft, or 27 bags of 1 cu ft. Bulk compost typically costs a third of the bagged price, so anything over one yard is worth ordering loose.
How much does a cubic yard of compost weigh?
Around 800 to 1,000 lb, depending on moisture. That is less than half the weight of topsoil, so a half-ton pickup can carry a full cubic yard without trouble.
How thick should compost be for topdressing a lawn?
A quarter to half an inch, no more. Thicker layers smother the grass. Spread it, then rake or brush it down between the blades so the compost reaches soil level.
Can I plant directly into pure compost?
It is not advisable. Pure compost holds too much water, settles heavily and can be too rich in nutrients for seedlings. Mix it with topsoil at roughly one part compost to three parts soil for beds.