Mulch Calculator
Find the cubic yards or number of bags of mulch your beds need at 2, 3 or 4 inches deep.
Quick estimating rule of thumb
For mulch: length (ft) × width (ft) × depth (in) ÷ 324 = cubic yards. One yard covers about 160 sq ft at 2 inches, or 108 sq ft at 3 inches. Most beds take 2 to 3 inches; add 10% because mulch settles as it breaks down.
This mulch calculator converts the size of your beds and the depth you want into cubic yards of bulk mulch or the number of 2-cubic-foot bags, and draws the area to scale as you type.
It works for wood and bark mulch. Switch to the rubber mulch calculator for playground rubber, which is denser and sold differently.
How deep should mulch be?
Two to three inches is right for most planting beds. Go to a full three to four inches for weed suppression in shrub borders and around trees, but keep it pulled back a few inches from trunks and stems. Piled against bark it holds moisture and invites rot.
Refreshing existing mulch usually means adding one inch, not a full layer. Rake the old mulch to break any crust first, then top up to the finished depth.
Bags or bulk?
Bagged mulch is sold in 2-cubic-foot bags, so it takes 13.5 bags to equal one cubic yard. Bulk mulch from a landscape yard is usually cheaper per yard once you pass roughly 8 to 10 bags, and it saves a lot of plastic, but you need somewhere to dump it and a way to move it.
One cubic yard of mulch covers about 160 square feet at 2 inches deep, or about 108 square feet at 3 inches.
Measuring irregular beds
Curved island beds and borders are rarely clean rectangles. Break the space into rectangles, triangles and circles you can measure, run each through the calculator and add the results. For a long border, treat it as a rectangle using the average width. Over-estimating slightly is cheap insurance. Running out mid-bed means a second trip.
Common mulching mistakes
Volcano mulching. Piling mulch against a trunk traps moisture and rots the bark, so keep it 3 inches clear of stems.
Going too deep. More than 3 to 4 inches suffocates roots and sheds water instead of holding it.
Not accounting for what is already there. Refreshing beds usually needs only 1 inch of new mulch, not a full layer.
Buying bags for a big job. Past 8 to 10 bags, bulk mulch is cheaper and saves a stack of plastic.
| Material | lb / ft³ | tons / yd³ | Sold by | Coverage per yd³ |
|---|---|---|---|---|
| Shredded hardwood / bark | 18–22 | 0.45 | yd³ or 2 ft³ bag | ~160 ft² at 2″, ~108 ft² at 3″ |
| Wood chips (arborist) | 15–20 | 0.40 | yd³ | ~160 ft² at 2″ |
| Rubber mulch (playground) | 35–50 | 0.63 | bag or pallet | ~2 ft² per ft³ at 6″ |
| Pine straw | n/a | n/a | bale | ~40–50 ft² per bale |
| Compost mulch | 40–50 | 0.55 | yd³ | ~160 ft² at 2″ |
Frequently asked questions
How many bags of mulch are in a cubic yard?
A cubic yard is 27 cubic feet, and mulch bags hold 2 cubic feet, so it takes 13.5 bags to make a cubic yard.
How much does a yard of mulch cover?
About 160 square feet at 2 inches deep, 108 square feet at 3 inches, and 81 square feet at 4 inches.
How deep should mulch be?
Two to three inches for most beds, three to four inches for weed control around trees and shrubs. More than four inches can starve roots of air.
How much does a cubic yard of mulch weigh?
Wood mulch is mostly air, roughly 0.4 to 0.5 tons per cubic yard dry, more when wet. That is why it is almost always sold by volume, not weight.
Is bulk mulch cheaper than bags?
Usually yes, once you need more than about 8 to 10 bags. Bulk mulch also cuts down on plastic waste, but you need space for the pile and a wheelbarrow to move it.
How often should I replace mulch?
Top up wood mulch by about an inch each year as it breaks down. A full replacement every two to three years keeps colour and depth consistent.
Should I remove old mulch first?
No need in most cases. Rake it to break up any matted crust, then add fresh mulch to reach the finished depth. Remove it only if it is compacted, mouldy or harbouring pests.
How much mulch do I need for a 200 square foot bed?
About 1.25 cubic yards at 2 inches deep, or roughly 17 bags. At 3 inches it is about 1.85 cubic yards.
How much mulch do I need for a 1,000 square foot area?
At 3 inches deep, about 9.25 cubic yards, or roughly 125 bags of 2 cubic feet. At 2 inches it is about 6.2 cubic yards.
Is dyed mulch safe for gardens?
Mulch dyed with iron oxide (brown, red) or carbon (black) is generally considered safe for ornamental beds. Avoid dyed mulch made from recycled construction wood around vegetables.
How long does wood mulch last?
A hardwood mulch layer holds colour for one season and structure for two to three years before it breaks down enough to need a full refresh. Top up about an inch each spring.
Should I put landscape fabric under mulch?
In shrub and rock beds, yes. In annual and perennial beds, skip it. Fabric blocks the mulch from improving the soil and roots grow into it.
How much does a scoop of mulch cover?
A "scoop" at most yards is a half or two-thirds of a cubic yard. A half-yard scoop covers about 80 square feet at 2 inches deep.