How much mulch do I need?
Multiply the area in square feet by the depth in inches, then divide by 324. That gives cubic yards, the unit bulk mulch is sold in. Clemson Extension uses the same shortcut: one cubic yard spread 1 inch deep covers 324 square feet.
Worked example
A 40 × 6 ft bed is 240 ft². At 3 inches deep that is 240 × 3 ÷ 324 = 2.22 cubic yards. Add 10% for settling and uneven ground and you get 2.44 yards, or 33 bags of 2 cu ft.
How far does mulch go?
| Depth | 1 cubic yard covers | One 2 cu ft bag covers | One 3 cu ft bag covers |
|---|---|---|---|
| 1 in | 324 ft² | 24 ft² | 36 ft² |
| 2 in | 162 ft² | 12 ft² | 18 ft² |
| 3 in | 108 ft² | 8 ft² | 12 ft² |
| 4 in | 81 ft² | 6 ft² | 9 ft² |
How deep should mulch be?
| Project | Depth | Usual mulch |
|---|---|---|
| New flower bed | 2–4 in · 5–10 cm | Shredded hardwood mulch |
| Top up a bed | 1–2 in · 2.5–5 cm | Shredded hardwood mulch |
| Tree ring | 2–4 in · 5–10 cm | Wood chips (arborist) |
| Woodland path | 3–4 in · 7.5–10 cm | Wood chips (arborist) |
| Playground | 12 in installed · 30 cm | Playground wood fiber |
| Rubber mulch bed | 1.5–2 in · 4–5 cm | Rubber mulch |
- Two to three inches suits most beds and shrubs. Iowa State Extension recommends 3 to 4 inches of wood chips or shredded bark on well-drained sites, and 2 to 3 inches on heavy soil.
- Keep mulch at least 6 inches away from tree trunks. Mulch piled against bark invites rot and rodents.
- For playgrounds, the U.S. Consumer Product Safety Commission recommends keeping at least 9 inches of loose-fill wood mulch, and installing 12 inches because it packs down by about a quarter.
Types of mulch
Weights are rough loose figures. Mulch soaks up water, so a wet yard can weigh much more than a dry one.
| Mulch | Approx. lb / yd³ | Bag size | Good for |
|---|---|---|---|
| Shredded hardwood mulch | 600 | 2 cu ft | The most common bed mulch. The fibres knit together, so it stays put on slopes. |
| Bark nuggets | 500 | 2 cu ft | Chunky pine bark. Long-lasting, but it floats and washes out on slopes. |
| Cedar mulch | 500 | 2 cu ft | Light, aromatic and slow to break down. |
| Wood chips (arborist) | 600 | 2 cu ft | Coarse mixed chips, often cheap or free from tree services. Good for paths and around trees. |
| Dyed mulch (black, brown, red) | 600 | 2 cu ft | Shredded wood coloured to hold its look longer than natural mulch. |
| Rubber mulch | 700 | 0.8 cu ft | Recycled rubber that does not break down. Mostly used under play sets. |
| Playground wood fiber | 500 | 2 cu ft | Engineered wood fiber for play areas. It packs down by about a quarter, so it is installed deeper than the depth you need to keep. |
Bags or bulk?
Bagged mulch usually comes in 2 cu ft bags, so it takes 13.5 bags to make a cubic yard. Bags are easy for a single bed or a quick top-up. Once you need more than a yard or two, bulk delivery usually costs less per yard and saves a lot of trips to the store.
Common questions
How many bags of mulch are in a yard?
A cubic yard is 27 cubic feet, so it takes 13.5 bags of 2 cu ft or 9 bags of 3 cu ft to make one yard.
How much area does a yard of mulch cover?
About 324 square feet at 1 inch deep, 162 at 2 inches, 108 at 3 inches and 81 at 4 inches.
How deep should mulch be?
Two to three inches is the usual guidance for beds and around shrubs. Iowa State Extension suggests 3 to 4 inches of wood chips on well-drained sites and 2 to 3 inches on heavy soil.
How much does a yard of mulch weigh?
Roughly 400 to 800 lb, depending on the type and how wet it is. That is why mulch is sold by volume rather than weight.
Should I remove old mulch before adding more?
Usually not. Rake it to loosen any matted crust and add enough new mulch to bring the total back to 2 to 3 inches. Piling more on every year can smother roots.
Sources: Clemson Extension, Mulch Matters; Iowa State Extension, mulch depth around trees and shrubs; CPSC Public Playground Safety Handbook. More on how we calculate.