Free tool
Mulch calculator for tree rings and beds
By Umair Nawaz, founder of Lirevon Updated How we test tools
Add each tree ring, round bed or rectangle bed. Pick a depth. You get cubic yards, bags and a cost estimate from your own prices. Tree rings leave a gap at the trunk, so you do not pile mulch against the bark. For homeowners and for tree crews who spread chips.
1. The areas
One row per area. For several trees with the same ring, set "How many". Measure in feet. Trunk width is in inches, measured across the trunk at chest height.
2. Depth and extras
3. Prices (optional)
Leave at 0 to skip the cost lines. Use your local prices.
Mulch estimate
Mulch job
Cubic yards (with extra)
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Bags needed
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Cubic feet
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Area covered
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Depth
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Estimate only, built from the numbers entered. Real coverage changes with the mulch type, how it is spread and how much it settles.
How the math works
- Rectangle bed area = length × width, in square feet.
- Round bed area = 3.1416 × (width across ÷ 2)².
- Tree ring area = the full circle minus the bare circle at the trunk. The bare circle reaches half the trunk width plus your gap. Inches are turned into feet by dividing by 12.
- Cubic feet = total area × depth in inches ÷ 12.
- With extra = cubic feet × (1 + extra %).
- Cubic yards = cubic feet with extra ÷ 27.
- Bags = cubic feet with extra ÷ bag size, rounded up to a whole bag.
- Bulk cost = yards × your price per yard + delivery. Bag cost = bags × your price per bag.
Tree ring guide
Mulch the tree, not the trunk
Good mulch keeps soil moist, keeps mowers and string trimmers off the bark and cuts down on weeds. Piled the wrong way, it can hurt the tree. These are the common rules from extension services and arborists.
Do
- Spread it flat, about 2 to 4 inches deep.
- Leave a few inches of bare soil next to the trunk.
- Keep the root flare, where the trunk widens at the base, in sight.
- Make the ring wide. Out toward the drip line is better where you can.
- Rake old mulch loose and top it up only when it gets thin.
Avoid
- Volcano mulching: tall cones of mulch piled against the trunk.
- Adding a fresh thick layer every year on top of the old one.
- Plastic sheets under mulch around trees, which can block air and water.
- Small, narrow rings that only cover the base of the trunk.
- Guessing when the trunk has a wound, rot or a wire left on it. Ask a local arborist to look first.
| Depth | Square feet per cubic yard | 2 cu ft bags per 100 sq ft |
|---|---|---|
| 2 inches | 162 | about 8.3 |
| 3 inches | 108 | 12.5 |
| 4 inches | 81 | about 16.7 |
Want to know more about a tree before you mulch it? Browse our tree species guides. Hiring someone for tree work? Start with our guides for homeowners.
Questions about mulch
How do I work out how much mulch I need?
Measure the area in feet. For a circle, use its width across. For a bed, use length and width. Multiply the area by the depth in inches and divide by 12. That gives cubic feet. Divide by 27 for cubic yards. This tool does it for each area and adds them up.
How deep should mulch be around a tree?
Most extension and arborist guides suggest about 2 to 4 inches. Fine mulch can sit at the lower end, coarse wood chips at the higher end. Deeper is not better. Too much mulch can keep roots short of air and water.
What is volcano mulching and why is it bad?
It is mulch piled in a tall cone against the trunk. The bark stays wet, which invites rot, insects and rodents, and roots can start to grow up into the pile and circle the trunk. Keep mulch flat and pulled back from the trunk so the root flare, where the trunk widens at the base, stays visible.
How far from the trunk should mulch stop?
Leave a small gap of bare soil next to the bark. Many guides say a few inches. This tool leaves a gap you choose (3 inches to start, change it) and takes that space out of the ring.
How wide should a tree mulch ring be?
Wider is better. A ring a few feet out from the trunk is a good start for a young tree. For a bigger tree, spread it toward the drip line, the edge of the branches, where the lawn and use of the yard allow it.
How many bags are in a cubic yard?
A cubic yard is 27 cubic feet. That is 13.5 bags of 2 cubic feet or 9 bags of 3 cubic feet. Check the bag label, because sizes vary. You can type any bag size into the tool.
Should I buy bulk mulch or bags?
For small jobs, bags are easy to carry and store. For larger areas, bulk by the yard is often cheaper, but delivery fees can change the math. Type your own local prices into the tool to compare both. The cost lines are estimates from your numbers.
Why add extra for waste and settling?
Mulch settles after it is spread and rain packs it down. Edges and uneven ground also use more than the math says. Adding about 5 to 10 percent is a common starting point. Change it to fit your job.
Can tree crews use this for wood chip jobs?
Yes. Many crews offer chips back to the customer or spread them as mulch. Use this to tell a customer how many yards their beds and rings will take, then use our chip volume calculator to see how many yards a job makes.
Is anything I type sent to Lirevon?
No. The math runs in your browser. Your numbers are only kept in this browser on this device so the form is filled in next time. Clear your browser data to remove them.
More tree facts: tree species guides, tree care by state, tree problems, root flare and critical root zone.
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