Mulch Calculator
Estimates only. Confirm quantities with your supplier before ordering.
One cubic yard of mulch covers about 108 square feet at a 3-inch depth, so a typical 200 sq ft bed needs roughly 1.85 cubic yards — about 25 standard 2-cubic-foot bags. Mulch is sold by volume, so the type you pick changes the look and how long it lasts, not the amount you need. Set your area and depth below for exact cubic yards, bag count, and cost.
Mulch types by depth, longevity, and use
| Mulch type | Recommended depth | Longevity | Best for | Notes |
|---|---|---|---|---|
| Shredded hardwood | 2–3 in | 1–2 seasons | Beds, slopes | Knits together and resists washing away; decomposes slowly. |
| Pine bark (shredded) | 2–3 in | 2+ years | Beds, foundations | Dark and attractive; breaks down slower than hardwood. |
| Pine bark nuggets | up to 4 in | 2+ years | Beds, borders | Large nuggets float and can wash out of beds in heavy rain. |
| Pine needles (straw) | 2–3 in | 1 season | Slopes, acid-lovers | Interlock and stay put on slopes; let air and water through. |
| Wood chips | 2–3 in | up to 2 years | Paths, trees | Inexpensive; fresh chips draw nitrogen and may attract termites. |
| Shredded leaves | up to 2 in | 1 season | Beds, vegetable plots | Never deeper than 2 in — whole or thick leaves mat and block water. |
| Grass clippings | up to 2 in | 1 season | Vegetable gardens | Use dry, seed- and herbicide-free clippings; build up gradually to avoid matting. |
How to estimate mulch
Mulch is estimated by volume. Multiply your bed area in square feet by the depth in inches and divide by 324 to get cubic yards — the shortcut this calculator runs is length × width × (depth ÷ 12) ÷ 27. The 324 figure comes straight from the geometry: one cubic yard is 27 cubic feet, which spread one inch thick covers 324 square feet. Because mulch sells by the bag or the loose yard, the calculator gives you both so you can match whichever your supplier quotes.
Type changes longevity, not volume
A cubic yard of shredded hardwood and a cubic yard of pine nuggets fill exactly the same space, so switching materials never changes how many yards you need. What it changes is the recommended depth and how often you re-mulch: fine bark and shredded leaves break down in a season or two, while pine bark holds up for a couple of years. If you'd rather use decorative stone that doesn't decompose, run the stone calculator for tonnage by stone type. Use the comparison table above to pick a type, then estimate the volume here.
Rubber and rock mulch: no annual refresh
Rubber mulch (shredded recycled tire) and decorative rock are inorganic, so they don't break down or feed the soil the way bark and wood do. That's the main reason to choose them: a rubber or stone layer can hold up for many years without the yearly top-up organic mulch needs, which often offsets the higher upfront price. Estimate rubber mulch by volume exactly as you would bark — set your area and depth above — but note it's usually sold in bags by weight rather than the 2-cubic-foot volume used for wood, so go by the coverage printed on the bag for the count. For loose stone instead of shredded rubber, the stone calculator and gravel calculator return tonnage by rock type, since stone is bought by weight.
Playground mulch needs far more depth
Playground surfacing is the one use where the 2–3 inch rule doesn't apply. The U.S. Consumer Product Safety Commission recommends maintaining at least 9 inches of loose-fill material — wood mulch, engineered wood fiber, or shredded rubber — under equipment up to about 7 feet high, and because loose-fill compresses and displaces, it should be installed around 12 inches deep to settle to that 9 inches. At a 9-inch compressed depth, wood mulch protects against falls from as high as 10 feet. That depth changes the volume dramatically: a play area needs roughly three times the mulch of the same area in a 3-inch garden bed. Set the depth field above to your target surfacing depth to size a playground order.
Common mistakes
- Mulching too deep. Piling fine mulch past 3 inches suffocates roots and holds water against stems. Clemson Extension caps fine bark and wood mulch at 2–3 inches; only coarse nuggets go to 4.
- Volcano mulching around trees. Heaping mulch against the trunk invites rot, pests, and girdling. Keep a 2–4 inch ring spread to the drip line and a few inches clear of the bark.
- Re-mulching to full depth every year. Existing beds usually need only a 1–2 inch top-up. Measure what's already there and add the difference rather than a whole new layer. For areas where mulch washes away frequently, switching to gravel may be more cost-effective long-term.
- Irregular beds. This calculator handles rectangles and circles. For a curved or L-shaped bed, split it into simple sections, run each, and add the cubic yards together.
Frequently asked questions
How much mulch do I need for my yard?
Multiply the bed area in square feet by the depth in inches, then divide by 324 to get cubic yards. For example, a 200 sq ft bed at 3 inches deep needs about 1.85 cubic yards, or roughly 25 standard 2-cubic-foot bags. Enter your real dimensions above for an exact figure in both yards and bags. Most beds want a 2–3 inch layer, so depth is the input that changes the total most.
How many cubic feet are in a yard of mulch?
There are 27 cubic feet in one cubic yard of mulch. Since retail bags are usually 2 cubic feet, that works out to 13.5 bags per cubic yard. Buying in bulk by the yard is almost always cheaper per cubic foot than bags once you need more than about 6–8 bags, but bags are easier to handle for small beds.
How many bags of mulch are in a cubic yard?
It takes 13.5 standard 2-cubic-foot bags to make one cubic yard, since a cubic yard is 27 cubic feet. If your store sells 1.5-cubic-foot bags you need 18 per yard, and 3-cubic-foot bags take 9 per yard. Because bag counts always round up, ordering a single bulk yard often beats buying 14 separate bags for both price and effort.
How much does a cubic yard of mulch cover?
One cubic yard covers 324 square feet at 1 inch deep, about 162 square feet at 2 inches, or roughly 108 square feet at 3 inches. Coverage drops as depth increases because you spread the same volume over a thicker layer. A single 2-cubic-foot bag covers about 12 square feet at 2 inches or 8 square feet at 3 inches.
How deep should mulch be?
Apply 2–3 inches for most garden and flower beds and 3–4 inches around trees and shrubs, per Clemson Extension guidance. Fine bark, wood, and shredded-leaf mulches should not exceed 3 inches because deeper layers can suffocate roots, while coarse pine-bark nuggets can go up to 4 inches. When refreshing an existing bed, only top up to that range rather than adding a full new layer each year.
Should mulch touch the trunk of a tree?
No — keep mulch a few inches clear of the trunk and never pile it against the bark. The Arbor Day Foundation recommends a 2–4 inch ring spread out to the drip line, not a cone heaped against the stem. "Volcano mulching" traps moisture against the bark, invites rot and pests, and can girdle the tree over time.
How much extra mulch should I order for waste?
Add about 5–10 percent to the calculated volume. Unlike gravel, mulch does not compact much, but uneven beds, edging losses, and rounding up bag counts still eat into coverage. The overage field above builds this buffer in; use the higher end for irregular beds or when you are covering bare soil for the first time rather than topping up.
Is it cheaper to buy mulch in bags or bulk?
Bulk mulch by the cubic yard is usually cheaper per cubic foot than bags, often by a wide margin, once you need more than roughly 6–8 bags. Bags win only for small beds where a bulk delivery is impractical, or when you can't store a loose pile. Enter a price per yard or per bag above and the calculator estimates the cost for the amount you actually need.
How much rubber mulch do I need?
Estimate rubber mulch by volume the same way as wood mulch — bed area in square feet times depth in inches, divided by 324 for cubic yards. The difference is at the store: rubber mulch is usually sold in bags rated by weight rather than the 2-cubic-foot volume used for bark, so match the calculated volume to the coverage printed on the bag rather than assuming 2 cubic feet each. Rubber costs more upfront but doesn't decompose, so there's no annual refresh.
How deep should playground mulch be?
Maintain at least 9 inches of loose-fill surfacing — wood mulch, engineered wood fiber, or shredded rubber — under playground equipment up to about 7 feet high, per the U.S. Consumer Product Safety Commission. Because loose-fill compresses and scatters underfoot, install it around 12 inches deep so it settles to 9. That's roughly three times the depth of a garden bed, so set the depth field above to your surfacing target rather than the usual 2–3 inches when sizing a play area.
Related calculators
Sources
- Mulch (HGIC 1604)Clemson Cooperative Extension, Home & Garden Information CenterDepth-by-type guidance (2–3 in for fine mulches, up to 4 in for coarse nuggets) and the coverage rule that one cubic yard covers 324 sq ft at 1 inch deep.
- Proper Mulching TechniquesArbor Day FoundationTree and shrub mulching guidance — a 2–4 inch layer spread to the drip line, kept clear of the trunk to avoid rot and girdling.
- Public Playground Safety Handbook (Pub. 325)U.S. Consumer Product Safety CommissionPlayground loose-fill surfacing depth — maintain at least 9 inches under equipment up to about 7 ft, and the critical-height rating that wood mulch at 9 in compressed protects falls up to 10 ft.