Mulch & Soil Calculator
Mulch, soil or gravel volume for a rectangular, round or triangular bed: cubic yards or m³, bags to buy, and an approximate weight for wood chips or compost. How it works
Use the Mulch & Soil Calculator
About the Mulch & Soil Calculator
A 10 × 10 ft bed covered 3 inches deep needs 25 ft³ of mulch, which is 0.93 cubic yards or 13 bags of 2 ft³. The mulch calculator multiplies the bed area by the depth, with the depth turned from inches into feet, and divides cubic feet by 27 for cubic yards. A round bed 10 ft across at the same depth takes 19.6 ft³ (0.73 cubic yards). Topsoil, compost and gravel work the same way, because the main result is a volume; an optional estimate gives the approximate weight of wood chips or compost.
Mulch for 100 sq ft (10 × 10 ft) by depth
| Depth | Cubic feet | Cubic yards | 2 ft³ bags | 3 ft³ bags |
|---|---|---|---|---|
| 1 in | 8.33 | 0.31 | 5 | 3 |
| 2 in | 16.67 | 0.62 | 9 | 6 |
| 3 in | 25.00 | 0.93 | 13 | 9 |
| 4 in | 33.33 | 1.23 | 17 | 12 |
| 6 in | 50.00 | 1.85 | 25 | 17 |
For a bed of a different size, scale by its area: 200 sq ft takes twice these volumes. Bag counts are rounded up for each bed, so add volumes first and divide once.
Mulch for 10 m² (5 × 2 m) by depth
| Depth | Cubic meters | Liters | 50 L bags | 100 L bags |
|---|---|---|---|---|
| 5 cm | 0.500 | 500 | 10 | 5 |
| 7.5 cm | 0.750 | 750 | 15 | 8 |
| 10 cm | 1.000 | 1000 | 20 | 10 |
How to use this tool
- Pick ft (depth in inches), in, m (depth in cm) or cm. The fields are saved in this browser until you press Clear Saved Values.
- Choose the bed shape (rectangle, circle or triangle), then enter its length and width, diameter, or base and height, and the depth you want to fill.
- Read the volume (cubic yards and cubic feet, or m³ and liters) and the number of bags of 2 and 3 ft³, or 50 and 100 L, rounded up. Pick wood chips or compost under Weight estimate for an approximate weight.
Frequently asked questions
- How many square feet does a cubic yard of mulch cover?
- A cubic yard is 27 ft³, so it covers 324 sq ft at 1 inch, 162 sq ft at 2 inches, 108 sq ft at 3 inches and 81 sq ft at 4 inches. Put the other way, 100 sq ft at 3 inches takes 0.93 cubic yards.
- How many bags of mulch do I need?
- Divide the cubic feet by the bag size and round up. The default 10 × 10 ft bed at 3 inches is 25 ft³: 13 bags of 2 ft³ or 9 bags of 3 ft³. In metric the tool counts 50 L and 100 L bags; for any other bag size, divide the volume by the size printed on the bag.
- How deep should mulch be?
- Cornell’s weed management guide recommends keeping a mulch layer of 2 to 4 inches, which holds back annual weeds by keeping light off the soil. The same guide says to clear the weeds already there before you spread it. The calculator starts at 3 inches.
- Can it work out tons of gravel or topsoil?
- No. For gravel and topsoil it gives the volume only, because no density for them was taken from a source. They are often sold by weight, so ask the supplier how many tons make a cubic yard (or a cubic meter) of that material and multiply by the volume shown. The weight estimate covers wood chips or bark and compost only.
- How much does a cubic yard of mulch weigh?
- About 533 lb for wood chips or bark and 1,011 lb for compost, from the tool’s estimate for 27 ft³ (a 9 × 9 ft bed 4 inches deep). It uses 316 kg/m³ for wood chips, the midpoint of the 445 to 620 lb/yd³ in the USDA NRCS Illinois mulching tables, and 600 kg/m³ for compost, from Oregon State University Extension’s figure of about 1,000 lb/cu yd for screened compost at 50% moisture. Wet or packed loads weigh more: OSU gives 800 to more than 1,600 lb/cu yd for compost.
- Should I order extra for settling?
- The calculator does not add any. Its tip suggests adding 10%: 25 ft³ becomes 27.5 ft³, which is 14 bags of 2 ft³ instead of 13.
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