Tools · Mulch
Mulch calculator: how much mulch do you need?
Enter the size of your bed or tree ring and the depth you want. The calculator gives the volume in cubic feet and cubic yards, and how many bags to buy.
Enter your measurements to see how much mulch to buy.
- Area
- —
- Volume
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- Bulk order
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- 2 cu ft bags
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- 3 cu ft bags
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How the calculation works
Mulch is sold by volume, so the calculator multiplies the area you want to cover by the depth. Area in square feet times depth in inches, divided by 12, gives cubic feet. Divide cubic feet by 27 to get cubic yards, the unit bulk suppliers use. Bag counts are rounded up to whole bags.
Two numbers are worth remembering:
- One cubic yard covers about 108 square feet at 3 inches deep.
- A 2-cubic-foot bag covers about 8 square feet at 3 inches deep.
How deep to spread mulch
| Mulch | Depth |
|---|---|
| Large pine bark nuggets | 3–4 inches |
| Arborist wood chips | 3–4 inches |
| Shredded bark and hardwood | 2–3 inches |
| Straw and shredded leaves in vegetable beds | 2–3 inches |
Measure what is already there before you buy. If an existing layer is still 2 inches deep, you only need enough to bring it back up to 3 or 4. Keep mulch at least 3 inches away from trunks and stems. The mulch guide explains why, and which mulch lasts longest.
Bulk or bags?
For anything bigger than a few small beds, bulk delivery by the cubic yard usually costs far less than bags. Bags are easier for small jobs, tight access, or a car trunk. Suppliers often sell in half-yard steps, so round your bulk order up. A little extra fills low spots.
Choosing what to buy? Read mulch that lasts for why large pine bark nuggets outlast shredded mulch, and where something finer works better.
Sources
- Iowa State University Extension: Using mulch in the garden — depth by texture.
- Penn State Extension: Mulching landscape trees — depth and clearance from the trunk.