Compost Volume & Cost Calculator
Results update as you type
Your Results
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Cubic Yards
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Cubic Feet
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Bags (1 cu ft)
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Bags (2 cu ft)
Estimated Material Cost (2026 prices)
| Option | Est. Cost | Notes |
|---|---|---|
| Bulk compost | — | $20–$50/cu yd, material only |
| Bagged (1 cu ft bags) | — | $3–$10/bag retail |
| Premium / biochar blend | — | $80–$125/cu yd bulk |
ⓘ Delivery adds $40–$150 per load. Many municipalities offer free or discounted compost — check local programs before buying.
* Add 10–15% overage for waste and uneven areas.
Compost Depth by Application
| Application | Compost Depth | Notes |
|---|---|---|
| New garden bed | 3–4 inches | Till into top 6–8” of existing soil. |
| Existing garden top-dress | 1–2 inches | Apply annually in fall or spring. |
| Lawn top-dressing | ¼–½ inch | Rake lightly after spreading. Ideal in fall. |
| Raised bed fill (mix) | Mix 20–30% compost with topsoil | Don’t use pure compost — it compacts and can burn roots. |
| Transplanting (hole amendment) | Mix 25% compost into backfill | Improves drainage and root establishment. |
How We Calculate This +
Formula
Area × (Depth ÷ 12) ÷ 27 = Cubic Yards
Key Assumptions
- Standard bag sizes: 1 and 2 cu ft
- Add 10% for settling after application
Price ranges based on national averages from HomeGuide, Angi, and LawnStarter. Updated May 2026.
How to Use the Compost Calculator
- 1 Choose your bed shape — Rectangle for standard beds, circle for round features, or Raised Bed for enclosed planter boxes (tip shown for correct depth).
- 2 Enter your dimensions in feet — Measure the length and width of the area you want to amend. For circular beds, enter the radius (half the diameter).
- 3 Select compost depth — Use the quick chips or type a custom depth. New beds typically need 3–4 inches; existing gardens need 1–2 inches as annual top-dressing.
- 4 Compare bulk vs. bagged — The results show cubic yards, bag count, and cost for both options so you can pick the most economical choice for your project size.
Frequently Asked Questions
How much compost do I need for a vegetable garden? +
For a new vegetable bed, apply 2 to 4 inches of compost and till it into the top 6 to 8 inches of soil. This improves drainage, aeration, and microbial activity. For existing beds you’ve been growing in, a 1 to 2 inch annual top-dressing each spring or fall is sufficient. Use the calculator above with your exact bed dimensions to get a precise cubic yard and bag count.
How often should I add compost to my garden? +
Most gardens benefit from compost once or twice a year. The most effective timing is in fall (after harvest, before the ground freezes) so nutrients can break down over winter, and again in early spring before planting. Vegetable gardens and heavy feeders like corn or squash may also benefit from a mid-season side-dress of compost around the base of plants.
Compost vs. topsoil: when to use which? +
Topsoil is the right choice when you need to raise the grade, fill a large volume, or establish a new lawn. Compost is the right choice when you want to improve fertility, drainage, and microbial life in existing soil. For raised beds, a common winning mix is 30% compost + 30% topsoil + 30% coarse material (perlite, aged bark, or coarse sand). Pure compost can compact over time and may have high nutrient concentrations that stress seedlings.
How many bags of compost per cubic yard? +
There are 27 cubic feet in one cubic yard. So you need 27 bags of 1 cu ft compost to equal one cubic yard. A 2 cu ft bag (the most common retail size) requires about 13–14 bags per cubic yard. For any project larger than about 20 sq ft at 3 inches deep (~0.2 cu yd), buying bulk compost from a landscape supplier is almost always more economical.
Is municipal free compost as good as purchased compost? +
Municipal compost (made from yard waste) is an excellent general amendment for lawns, existing beds, and non-food gardens. It’s often free or subsidized through local programs. For vegetable gardens and new food beds, premium purchased compost or a certified blend may offer a richer, more consistent nutrient profile. Always ask for a recent analysis if using municipal compost in a food garden, and confirm it’s tested for herbicide residues.
How to Buy Compost: Bulk vs. Bags and What to Look For
Compost is sold in two main forms: bagged at garden centers (1 or 2 cu ft bags, $3–$10 each) and bulk by the cubic yard from landscape suppliers ($20–$50/cu yd for standard compost, $80–$125 for premium blends). For most residential projects larger than 2–3 cubic yards, bulk compost is significantly more economical.
When to Buy Bags vs. Bulk
Bags make sense when you need a small amount (under 1 cubic yard), want a specific blend, or don’t have a way to haul loose material. Bulk is the right call for new bed builds, large lawn top-dressings, and raised bed fills where you need more than 1–2 cubic yards. Most landscape supply yards sell by the cubic yard with a standard dump truck delivery for $40–$150 extra.
What Makes a Good Compost?
- Dark, earthy smell — fully cured compost smells like forest floor, not ammonia or rot.
- Fine, crumbly texture — large chunks or recognizable plant material means it’s not finished composting.
- STA Certified — look for the Seal of Testing Assurance from the US Composting Council for verified maturity and pathogen testing.
- Low salt content — biosolid composts can be high in salts; check the EC (electrical conductivity) if using in a food garden.
Ready to order? Use the compost calculator above ↑ to get exact cubic yards and bag counts before calling your supplier.