How this compost calculator works
Compost math is thin-layer volume math — the depths are small, so the bag count and the rounding matter more than usual:
order = yd³ × (1 + allowance%) → rounded up to ¼ yd³ · 27 × 1 ft³ bags per yard
Worked example: compost for a 20 × 10 bed
200 ft² at a 2 in spread is 33.3 ft³ — 1.23 yd³. With 5% the order is 1.5 yd³: about $53 bulk or 35 bags (≈ $175). One yard covers 162 ft² at this depth, which is why a single scoop handles most gardens.
How much compost per square foot?
| Depth | 1 yd³ covers |
|---|---|
| ½″ (lawn topdress) | 648 ft² |
| 1″ | 324 ft² |
| 2″ | 162 ft² |
| 3″ | 108 ft² |
| Job | Depth |
|---|---|
| Lawn topdressing | ½″ |
| Annual bed feed | 1–2″ |
| New bed into poor soil | 2–3″ |
Compost FAQ
How much compost do I need?
Area × depth ÷ 12 ÷ 27: spreading 2 in over the default 20 × 10 ft bed is 1.23 yd³ — order 1.5 cubic yards with 5% allowance, or 35 one-cubic-foot bags. Bulk runs about $53 against $175 bagged at the defaults.
How many bags of compost are in a cubic yard?
27 of the common 1 ft³ bags — compost bags run smaller than mulch bags. That is why bagged compost turns expensive fast: the default job is 35 bags, already past the point where a bulk drop wins.
How deep should I spread compost?
1–2 inches worked into vegetable and flower beds each season, half an inch raked over lawns as topdressing, and up to 2–3 inches when building a new bed into poor soil. More is not better — compost is an amendment, not a growing medium on its own.
How much does a yard of compost weigh?
Roughly 1,000 lb — half a ton — finished and moderately moist, so the default 1.5-yard order is about 0.75 tons. Fresh, wet compost can push 1,400 lb a yard; a pickup handles a yard comfortably.
How much does compost cost?
Bulk finished compost typically runs $30–60 per cubic yard in 2026, with municipal programs often cheaper or free-load days. Bags work out to 3–4× bulk per yard; the two cost lines above make the comparison for your numbers.
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