Mulch Calculator
Cubic yards of mulch, topsoil or compost for a bed, or how many bags, at the depth you want, with how far one yard goes.
Mulch
0.93 yd³
or 13 bags of 2 ft³ · 17 bags of 1.5 ft³
- Area
- 100 ft²
- Volume
- 0.93 yd³
- Cubic feet
- 25 ft³
- 2 cu ft bagsthe usual mulch bag
- 13
- 1.5 cu ft bagsthe usual topsoil and compost bag
- 17
- One cu yd coversat this depth
- 108 ft²
- Bulk cost
- 32.41
Kalku is coming to iPhone and Android
The app keeps the whole yard in one place: mulch, topsoil and compost, gravel and sand bases, pavers, retaining walls and fences, each drawn in 3D as you type. It works with no signal in the garden centre and saves each bed with a note.
How it is worked out
Mulch is sold by volume, so the calculation is the bed's length × width × depth. Bulk deliveries are priced by the cubic yard (27 cubic feet); bags are sold by their own volume, usually 2 cubic feet for mulch and 1.5 for soil and compost. The calculator works out the cubic feet once and divides it by each bag size, rounding up, since a part bag still has to be bought.
Depth is the number that moves the answer most, and the one people guess. An inch more across a 100 square foot bed is another 8.3 cubic feet: four or five more bags. Measure a few spots on an existing bed before topping it up.
Worked example: a 20 × 5 ft bed, 3 inches deep
- Area: 20 ft × 5 ft = 100 ft².
- Volume: 100 ft² × 3/12 ft = 25 ft³, which is 25 ÷ 27 = 0.93 yd³.
- Bags: 25 ÷ 2 = 12.5, so 13 bags of 2 cu ft; or 25 ÷ 1.5 = 16.7, so 17 bags of 1.5 cu ft.
- At 3 inches one cubic yard covers 108 ft²; delivered in bulk at 35 a yard, the bed costs 32.41.
How far one cubic yard goes
| Depth | Covers |
|---|---|
| 1 in | 324 ft² |
| 2 in | 162 ft² |
| 3 in | 108 ft² |
| 4 in | 81 ft² |
| 6 in | 54 ft² |
Questions
How much does a yard of mulch cover?
A cubic yard is 27 cubic feet, so it covers 324 square feet one inch deep. At 2 inches that is 162 square feet, at 3 inches 108, and at 4 inches 81. The calculator shows the figure for the depth you enter.
How many bags of mulch make a yard?
Thirteen and a half 2 cubic foot bags, or eighteen 1.5 cubic foot bags. Mulch usually comes in 2 cubic foot bags and topsoil and compost in 1.5 cubic foot bags, so the calculator counts both, rounded up.
How deep should mulch be?
A common guide is 2 to 4 inches of mulch on a bed, and 4 to 6 inches of topsoil where you are building up soil. Freshly spread bulk material settles, so add 5 to 10% for a new bed.
Does it work for topsoil and compost?
Yes. The arithmetic is the same for anything sold by volume: length × width × depth. Only the bag size differs, which is why both are shown. Gravel and stone are sold by weight; use the gravel calculator for those.
