Mulch Calculator
Find out how much mulch you need for your beds — in cubic yards and 2 ft³ bags — with the coverage, formula, and depth guidance shown.
You need · incl. +10% extra
- Cubic feet
- 27.5 ft³
- Cubic meters
- 0.78 m³
- Pounds
- 815 lb
- Kilograms
- 370 kg
- Area
- 100 ft²
- Exact volume
- 0.93 yd³
- Density
- 0.4 t/yd³
- Bag size
- 2 ft³ bag
Order about 10% extra to top up thin spots and edges. Mulch breaks down over the season, so most beds need a fresh top-up layer each year rather than a full replacement.
Beds and around plants: 2–3 in (2 to suppress weeds, 3 ideal). Keep mulch off stems and trunks, and avoid going over 4 in.
The formula & constants
Volume = Area × Depth. Convert to cubic yards (1 yd³ = 27 ft³); bags = Volume in ft³ ÷ bag size (a standard bag is 2 ft³, so ~13.5 bags per yard).
| Mulch density (working value) | 0.4 tons/yd³ |
| Typical range | 0.3–0.5 tons/yd³ |
| Cubic-yard conversion | 1 yd³ = 27 ft³ |
| Recommended overage | +10% |
Mulch subtypes & their densities
| Subtype | Density |
|---|---|
| Shredded hardwood | 0.45 tons/yd³ |
| Pine bark / nuggets | 0.35 tons/yd³ |
| Wood chips | 0.4 tons/yd³ |
| Rubber mulch | 0.6 tons/yd³ |
Source: Typical wood mulch bulk density (~0.3–0.5 tons/yd³), per Inch Calculator. Densities vary with moisture and compaction — the weight figure is an estimate.
How much mulch do you need?
Mulch is the layer you spread over beds to lock in moisture, smother weeds, steady soil temperature, and finish the look. Organic mulches — shredded hardwood, bark, wood chips — slowly break down and feed the soil, which is why beds need a top-up most years. Rubber mulch does not decompose but is heavier and does not improve the soil; the calculator covers both, so pick the subtype that matches.
Two to three inches is the sweet spot. Less than 2 inches and weeds push through; more than about 4 inches can starve roots of air and trap too much moisture against stems. Spread it even, and pull it back a couple of inches from trunks and stems — piling mulch into "volcanoes" around trees rots the bark. The calculator defaults to 3 inches.
Mulch is sold loose by the cubic yard (bulk, much cheaper for big beds) and in 2 ft³ bags for small jobs — about 13.5 bags make a cubic yard. Use the cubic-yards figure to order bulk and the bag count for a quick garden-center run; order around 10% extra to top up thin spots and edges.
Frequently asked questions
How much mulch do I need?+
Multiply your bed area (length × width in feet) by your depth in feet for cubic feet, divide by 27 for cubic yards, or divide the cubic feet by 2 for standard bags. Enter your dimensions and depth above and the calculator does it live.
How many bags of mulch are in a cubic yard?+
About 13.5 of the standard 2 ft³ bags make one cubic yard (27 ÷ 2). For anything more than a couple of beds, bulk mulch by the yard is far cheaper than bags.
How deep should mulch be?+
Two to three inches for most beds — 2 inches to suppress weeds, 3 inches for the best moisture and weed control. Going much over 4 inches can suffocate roots and hold too much moisture against plants.
How much does a cubic yard of mulch cover?+
A cubic yard of mulch covers about 162 sq ft at 2 inches deep, 108 sq ft at 3 inches, or 81 sq ft at 4 inches. Set your depth above to see the exact area.
How many cubic yards of mulch do I need?+
Measure each bed and add the areas, set the depth to 2–3 inches, and read the cubic yards. As a guide, one cubic yard covers about 108 sq ft at the typical 3-inch depth.
How much does a yard of mulch weigh?+
Roughly 600–1,000 lb (about 0.3–0.5 US tons) per cubic yard for dry wood mulch — heavier when wet. Rubber mulch weighs more. Mulch is usually ordered by volume, not weight.
Is it cheaper to buy mulch in bulk or bags?+
Bulk is much cheaper per cubic yard once you need more than about 10 bags. Bags are convenient for a single small bed or a top-up; bulk delivery wins for a whole yard of beds.
How often should I add mulch?+
Organic mulch breaks down over a season, so most beds need a fresh 1–2 inch top-up each year to stay at the ideal 2–3 inch depth — not a full replacement. Rake the old layer first so it does not mat.
Should I order extra mulch?+
Yes — about 10% extra covers thin spots, edges, and settling. It is easier to finish a bed evenly with a little spare than to make a second trip.
Is this mulch calculator free?+
Yes — free, no sign-up, and it runs entirely in your browser, so nothing you enter is stored or sent anywhere.