Mulch & Soil Calculator
Calculate the volume of mulch, soil or compost needed to cover an area.
Results update as you type.
About this calculator
A mulch and soil calculator works out the volume of mulch, topsoil or compost needed to cover a garden bed to a chosen depth. It multiplies the bed area (length × width) by the depth to get a volume, reported in cubic yards (imperial) or cubic metres (metric), and estimates how many standard bags that is — a 2 cubic-foot bag in imperial, a 50-litre bag in metric. Add a second bed and a price per cubic yard or metre under advanced options.
Worked example: a 20 × 10 ft bed is 200 sq ft. At 3 inches deep that is 200 × (3 ÷ 12) = 50 cubic feet, which is 50 ÷ 27 ≈ 1.85 cubic yards, or about 25 two-cubic-foot bags. Doubling the depth to 6 inches doubles the volume.
Gardeners use it to order bulk mulch by the yard instead of over- or under-buying bags, to top up beds each season, and to compare the cost of bagged against bulk delivery.
Frequently asked questions
How do I calculate cubic yards of mulch?
Multiply the area in square feet by the depth in feet (inches ÷ 12), then divide by 27 to convert cubic feet to cubic yards. A 20×10 ft bed at 3 in deep is 200 × 0.25 = 50 cu ft, or about 1.85 cubic yards.
How deep should mulch be?
Two to three inches (about 5–8 cm) is typical for beds — enough to suppress weeds and hold moisture without smothering plants. Deeper is fine for paths but keep mulch off plant stems and trunks.
How many bags of mulch are in a cubic yard?
A cubic yard is 27 cubic feet, so it takes about 13–14 of the common 2 cubic-foot bags to equal one bulk yard. Once you need more than roughly 8–10 bags, bulk delivery by the yard is usually cheaper.
Can I use it for topsoil or compost instead of mulch?
Yes — the volume calculation is the same for any spread material, so it works for topsoil, compost, bark or wood chips. Only the depth guidance differs: soil and compost are often dug in or layered thicker than a decorative mulch topping.
How much area does a cubic yard of mulch cover?
One cubic yard spreads about 100 sq ft at 3 inches deep, 160 sq ft at 2 inches, or 300 sq ft at 1 inch — depth and coverage trade off directly. Enter your bed size and depth and the calculator does this conversion for you.
Should I remove the old mulch before adding more?
Usually you just top up — measure only the extra depth you want to add rather than the full layer, since decomposed old mulch feeds the soil. Refresh to about 2–3 inches total each season and keep it clear of stems and trunks.
API — use this calculator from code
Call this calculator as a free JSON endpoint — no key required. Send the field values below as query parameters or JSON. Read the full API docs →
Endpoint
GET https://calculator.free/api/v1/mulch/curl
curl "https://calculator.free/api/v1/mulch/?units=imperial&length=20&width=10&depth=3"JavaScript fetch()
const r = await fetch(
"https://calculator.free/api/v1/mulch/?" + new URLSearchParams({
"units": "imperial",
"length": "20",
"width": "10",
"depth": "3"
}));
const data = await r.json();
console.log(data.results);Results are estimates for general guidance only, not financial, medical or tax advice.