How to calculate mulch
Mulch is sold by volume: cubic yards when you buy in bulk, cubic feet when you buy bags. To figure out how much you need, find the area of the bed in square feet, multiply by the depth in feet, then convert to yards or divide by the bag size.
Cubic feet = area (sq ft) × depth (in) ÷ 12
Cubic yards = cubic feet ÷ 27
Bags = cubic feet ÷ bag size (cu ft), rounded up
Worked example: a 20 × 10 ft bed, 3 in. deep
- Area: 20 × 10 = 200 sq ft.
- Depth in feet: 3 ÷ 12 = 0.25 ft.
- Volume: 200 × 0.25 = 50 cu ft.
- Cubic yards: 50 ÷ 27 = 1.85 cu yd.
- 2 cu ft bags: 50 ÷ 2 = 25 bags (or 17 bags of 3 cu ft, or 34 bags of 1.5 cu ft).
If that same bed still has about 1 in. of old mulch, you only need to add 2 in.: 200 × 2 ÷ 12 = 33.3 cu ft, or 17 bags of 2 cu ft. Enter the old depth in the Existing mulch depth box and the calculator does this for you.
Round beds and tree rings
For a circle, measure the diameter, halve it to get the radius, then multiply the radius by itself and by 3.14. A tree ring 6 ft across has an area of 3 × 3 × 3.14 = 28.3 sq ft. At 3 in. deep that is 7.1 cu ft, or 4 bags of 2 cu ft. You can skip subtracting the trunk; the extra mulch covers the slight overlap at the edges.
How much area does a cubic yard of mulch cover?
One cubic yard is 27 cubic feet, enough to cover 324 sq ft at 1 in. deep. Divide 324 by your depth in inches to get coverage at any depth.
| Depth | 1 cubic yard covers | One 2 cu ft bag covers | One 3 cu ft bag covers |
|---|---|---|---|
| 1 in. | 324 sq ft | 24 sq ft | 36 sq ft |
| 2 in. | 162 sq ft | 12 sq ft | 18 sq ft |
| 3 in. | 108 sq ft | 8 sq ft | 12 sq ft |
| 4 in. | 81 sq ft | 6 sq ft | 9 sq ft |
How many bags of mulch are in a yard?
| Bag size | Bags per cubic yard | Bags for 100 sq ft at 3 in. |
|---|---|---|
| 1.5 cu ft | 18 | 17 |
| 2 cu ft | 13.5 | 13 |
| 3 cu ft | 9 | 9 |
The 2 cu ft bag is the standard size for shredded hardwood, dyed mulch and pine bark at most US home centers. Some bark nuggets, cypress and premium mulches come in 1.5 or 3 cu ft bags, so check the label before you multiply.
How deep should mulch be?
| Mulch type | Typical depth |
|---|---|
| Fine shredded hardwood, dyed mulch, compost | 2–3 in. |
| Pine straw or pine needles | 2–4 in. (settles quickly) |
| Coarse bark nuggets, wood chips | 3–4 in. |
| Annual top-up over existing mulch | 1–2 in. |
| Wood chips under playground equipment | 9 in. or more (see CPSC playground guidance) |
Fine mulch packs down tighter, so it needs less depth to block light and hold moisture. Coarse mulch has more air space and needs a thicker layer to do the same job. Going much deeper than 4 in. in planting beds can keep water and oxygen from reaching roots.
Mulching tips that save money and plants
- Pull mulch away from trunks. Leave a few inches of bare ground around tree trunks and shrub stems. Mulch piled against bark (the "mulch volcano") holds moisture against it and invites rot and pests.
- Keep it off the house. Leave a gap between wood mulch and your siding or foundation so the wall can dry out and you can spot termite tubes.
- Measure before you shop. Pace off curved beds or use a tape measure and split them into rectangles. Our square footage calculator handles odd shapes.
- Don't stack layers year after year. Old mulch breaks down, but if you add 3 in. every spring, beds can end up 6–8 in. deep. Check the depth with a trowel and add only what you need.
- Compare bags and bulk. Enter both prices above. Bulk mulch is usually priced per cubic yard plus a delivery fee, and many yards have a minimum order. For small jobs, bags are easier; for several yards, bulk often wins.
- Prepare the bed first. Pull weeds and edge the bed before mulching. A clean edge keeps mulch from washing into the lawn.
Planning a bigger yard project? If you are building new beds, use the topsoil calculator for the soil underneath, the gravel calculator for stone paths and borders, or the cubic yards calculator for any other bulk material.
Frequently asked questions
How many bags of mulch are in a cubic yard?
There are 13.5 bags of 2 cu ft mulch in a cubic yard, because a cubic yard is 27 cubic feet (27 ÷ 2 = 13.5). That works out to 18 bags of 1.5 cu ft or 9 bags of 3 cu ft.
How much area does a 2 cu ft bag of mulch cover?
A 2 cu ft bag covers about 12 sq ft at 2 in. deep, 8 sq ft at 3 in., or 6 sq ft at 4 in. Divide 24 by the depth in inches to get the coverage at any depth.
How many bags of mulch do I need for a 10×10 area?
A 10 × 10 ft bed is 100 sq ft. At 3 in. deep you need 25 cubic feet, which is 13 bags of 2 cu ft mulch (12.5 rounded up) or about 0.93 cubic yards in bulk.
How deep should mulch be?
Most beds do best with 2–3 in. of fine shredded mulch or 3–4 in. of coarse bark or wood chips. If last year's mulch is still there, a 1–2 in. top-up is usually enough.
Will a cubic yard of mulch fit in a pickup truck?
Usually, yes. Mulch is light, and a full-size pickup bed holds roughly 2 cubic yards when filled level with the bed rails. Smaller and short-bed trucks hold less, so ask the supplier to load by the scoop and cover the load with a tarp.
Should I remove old mulch before adding new mulch?
Usually not. Old mulch breaks down and improves the soil. Rake it to loosen any matted crust, then add only enough new mulch to bring the total back to 2–4 in. Remove it only if it is moldy, very deep or piled against stems.