Free Mulch Calculator
Use this mulch calculator to see how many cubic yards or bags of mulch you need for your beds.
Mulch is sold by volume: bulk by the cubic yard, bagged by the cubic foot (usually 2 or 3 cu ft bags). To know how much to buy, multiply the area of each bed by the depth you want, then convert to yards or bags.
A 3 inch layer is the usual target for weed control and moisture. If you are only topping up last year's mulch, 1 inch is often enough.
How much mulch do I need for a 10 × 12 bed?
A 10 × 12 ft bed at 3 in deep: 120 sq ft × 3 in ÷ 12 = 30 cu ft, plus 5% extra = 31.5 cu ft. Divide by 27 to get 1.17 cubic yards, which weighs about 0.41 tons, or 11 × 3 cu ft bags.
How deep should mulch be?
| Use | Depth | Notes |
|---|---|---|
| New flower and shrub beds | 3 in | Enough to block most weed seedlings. |
| Topping up existing mulch | 1 in | Rake the old layer first; keep the total, old plus new, to about 3 in. |
| Around trees | 2 to 3 in | Keep mulch 3 to 4 in away from the trunk, never piled against it. |
| Compacted or poorly drained soil | 2 in | Thinner layers let the soil breathe. |
| Vegetable garden paths | 3 to 4 in | |
| Fine mulch (shredded leaves, pine straw) | 1 to 2 in | Fine material packs down, so less is needed. |
Coverage per cubic yard and per bag
| Depth | Sq ft per cubic yard | Sq ft per 3 cu ft bag |
|---|---|---|
| 1 in | 324 | 36 |
| 2 in | 162 | 18 |
| 3 in | 108 | 12 |
| 4 in | 81 | 9 |
Buying tips
- One cubic yard equals 13.5 two-cubic-foot bags or 9 three-cubic-foot bags. Bulk usually works out cheaper once you need more than 2 or 3 yards, even after delivery. Enter both prices in the calculator to check.
- Most suppliers sell bulk mulch in half-yard steps, so the calculator rounds your order up to the next half yard.
- Bulk mulch is light but bulky: a half-ton pickup carries about 2 cubic yards before it is full.
- Wet mulch weighs about twice as much as dry. Ask for a dry load if you are moving it by wheelbarrow.
- Dyed red and black mulch need the same depth as natural mulch; the colour does not change the quantity.
How much does mulch weigh?
A cubic yard of mulch typically weighs 400 to 1,000 lb (0.2 to 0.5 tons). The calculator uses 700 lb (0.35 tons) per cubic yard. Moisture and grading change the weight, so if your supplier sells by the ton, ask for their figure.
Frequently asked questions
How many cubic yards of mulch do I need?
Multiply the bed area in square feet by the depth in inches, then divide by 324. A 10 × 12 ft bed at 3 inches needs 120 × 3 ÷ 324 = 1.11 cubic yards, or about 1.17 with 5% extra. The calculator above does this for several beds at once.
Is this a mulch bag calculator too?
Yes. The result shows how many 2 cu ft and 3 cu ft bags you need, and you can compare the bagged price with bulk under Extra and prices.
How many bags of mulch are in a yard?
One cubic yard is 27 cubic feet, so it equals 13.5 bags of 2 cu ft or 9 bags of 3 cu ft.
How much area does a yard of mulch cover?
One cubic yard covers about 324 sq ft at 1 inch deep, 162 sq ft at 2 inches, 108 sq ft at 3 inches and 81 sq ft at 4 inches.
How much does a yard of mulch weigh?
Usually 400 to 1,000 lb, depending on the wood and how wet it is. Our weight estimate uses about 700 lb per yard.
How deep should mulch be?
University extension services recommend 2 to 3 inches, including any old mulch still there. Use about 1 inch to refresh existing beds, and keep mulch 3 to 4 inches away from tree trunks.
How accurate is this mulch calculator?
The mulch calculator gives the exact volume for the measurements you enter, then adds 5% extra (you can change it). Weights use a typical 0.35 tons per cubic yard; real loads vary with moisture, so confirm with your supplier if you buy by the ton. Measure carefully: an error of one inch in depth changes a 3 inch layer by a third.
How the mulch calculator works
Volume = area × depth. Each area is worked out from its shape (length × width, π × radius², or ½ × base × height), converted to square feet, multiplied by the depth in feet, and added up. Cubic feet ÷ 27 = cubic yards.The extra percentage is then added, and bag counts are rounded up to whole bags. See how we calculate for every figure we use.