Screened soil and compost lose 10-20% of their volume once spread and watered.
Cubic feet per bag. Retail soil and compost bags run 0.75 to 1.5 ft³.
Quantity estimate for planning and buying. Rates vary by variety, region and product — check the label on what you actually buy.
How much compost, by job
Compost application depths are small, and the difference between jobs is large. Topdressing a lawn at a quarter-inch is about 0.8 cubic yards per 1,000 ft²; mulching a bed at 2 inches is 6.2. Same product, eight times the quantity.
| Job | Depth | Per 1,000 ft² |
|---|---|---|
| Lawn topdressing | 0.25-0.5 in | 0.8-1.6 yd³ per 1,000 ft² |
| New lawn, before seeding | 1 in | 3.1 yd³ per 1,000 ft² |
| Established beds, annual mulch | 1-2 in | 3.1-6.2 yd³ per 1,000 ft² |
| New bed, worked in | 2-3 in | 6.2-9.3 yd³ per 1,000 ft² |
| Heavy clay improvement | 3-4 in | 9.3-12.3 yd³ per 1,000 ft² |
Topdressing a lawn
A quarter to half an inch, brushed or raked in so the grass blades still show through. The point is to get organic matter down to the soil surface, not to bury the lawn — more than half an inch smothers grass, and it is the most common way people damage a lawn while trying to improve it.
Topdressing works best straight after core aeration, when the holes are open and the compost can fall into them. That combination is the single most effective thing you can do for compacted clay soil, and it is far more useful than adding fertilizer to soil that cannot hold water.
Beds and soil improvement
One to two inches a year on established beds, laid on the surface, is enough to maintain organic matter. There is no need to dig it in; earthworms are better at it and digging damages soil structure.
For a new bed on poor soil, 2-3 inches worked into the top 6-8 inches is a genuine improvement. On heavy clay you can go to 3-4 inches, but this is a multi-year project rather than a single fix — clay improves gradually and does not respond to one heavy dose.
A caution: compost is not potting mix and not a growing medium on its own. Seedlings planted into pure compost often struggle with excess nutrient and poor water retention. It is an amendment.
Common questions
How much compost per 1,000 square feet?
About 0.8 cubic yards for a quarter-inch lawn topdressing, 3.1 for a one-inch layer, and 6.2 for a two-inch bed mulch.
How thick should compost be on a lawn?
A quarter to half an inch, raked in so the grass still shows through. Any more smothers the grass. Do it right after core aeration for the best result.
Can I plant directly in compost?
Not ideally. Compost is an amendment, not a growing medium — it is high in nutrients and holds water poorly on its own. Mix it with soil, at roughly 30% of the total for a raised bed.
How much does a cubic yard of compost weigh?
Around 800-1,000 lb, well under soil at about 2,000 lb. A half-ton pickup can carry about a cubic yard of compost by weight.