Find out how much mulch you need for flower beds, tree rings, borders and play areas. Enter the size of each bed and the depth and this mulch calculator gives you cubic yards, the number of 2 and 3 cu ft bags and the cost. This free online mulch calculator works on any phone or computer, with no sign-up or download.
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Mulch needed
— cu yd
Quick answer: cubic yards of mulch = length × width (ft) × depth (in) ÷ 12 ÷ 27. One cubic yard covers 108 sq ft at 3 in deep and equals 13.5 bags of 2 cu ft or 9 bags of 3 cu ft.
Cubic yards = L (ft) × W (ft) × depth (in) ÷ 324
The 324 is 12 × 27: it turns inches into feet and cubic feet into cubic yards in one step.
Three beds: 20 × 4 ft, 12 × 3 ft and 10 × 10 ft, all 3 in deep.
80 + 36 + 100 = 216 sq ft. 216 × 3 ÷ 324 = 2 cu yd.
As bags: 54 cu ft ÷ 2 = 27 bags of 2 cu ft, or 18 bags of 3 cu ft.
| Bag size | Bags per cu yd | Covers at 2 in | Covers at 3 in |
|---|---|---|---|
| 1.5 cu ft | 18 | 9 sq ft | 6 sq ft |
| 2 cu ft | 13.5 | 12 sq ft | 8 sq ft |
| 3 cu ft | 9 | 18 sq ft | 12 sq ft |
Already have a pile, or comparing deliveries? The “Already have a load?” box in the calculator works this out for any amount.
| Depth | 1 cu yd covers | 1 bag of 2 cu ft covers |
|---|---|---|
| 1 in | 324 sq ft | 24 sq ft |
| 2 in | 162 sq ft | 12 sq ft |
| 3 in | 108 sq ft | 8 sq ft |
| 4 in | 81 sq ft | 6 sq ft |
| 6 in | 54 sq ft | 4 sq ft |
| Bed | Depth | Cubic yards | 2 cu ft bags | 3 cu ft bags |
|---|---|---|---|---|
| 10 × 3 ft border | 3 in | 0.28 | 4 | 3 |
| 20 × 4 ft foundation bed | 3 in | 0.74 | 10 | 7 |
| 10 × 10 ft bed | 3 in | 0.93 | 13 | 9 |
| 30 × 5 ft bed | 3 in | 1.39 | 19 | 13 |
| 50 × 4 ft top-up | 2 in | 1.23 | 17 | 12 |
| 100 × 3 ft path | 3 in | 2.78 | 38 | 25 |
Beds are rarely perfect rectangles. Use the shape closest to each bed, add it to the project total, and move on to the next. Curved beds can be measured as a rectangle using their average width.
Also: rectangular prism, bed, trench, room
V = L × W × H
L = length, W = width, H = height or depth.
Example: A flower bed along the house, 20 ft long and 4 ft deep, mulched 3 in deep: 20 × 4 × 0.25 = 20 cu ft = 0.74 cu yd, or 10 bags of 2 cu ft.
Also: square feet to cubic feet
V = A × d
A = area, d = depth or thickness.
Example: All the beds on a lot add up to 450 sq ft, mulched 3 in deep: 450 × 0.25 = 112.5 cu ft = 4.17 cu yd.
Also: round hole, post hole, tank, planter
V = π × r² × h
r = radius (half the diameter), h = height.
Example: A round island bed 8 ft across, 3 in deep: π × 4² × 0.25 = 12.6 cu ft = 0.47 cu yd, or 7 bags of 2 cu ft.
Also: around a tree, donut bed, circle with a hole
V = π × (R² − r²) × d
R = outer radius, r = inner radius (the part left bare), d = depth.
Example: A ring around a tree, 6 ft across with the 1 ft around the trunk left bare, 3 in deep: π × (3² − 0.5²) × 0.25 = 6.9 cu ft = 0.25 cu yd, or 4 bags of 2 cu ft.
Also: ramp, uneven depth, tapered bed
V = L × W × (h₁ + h₂) ÷ 2
L = length, W = width, h₁ and h₂ = depth at each end.
Example: A bed that you want 3 in deep at the front and 2 in at the back, 20 × 6 ft: 20 × 6 × (0.25 + 0.167) ÷ 2 = 25 cu ft = 0.93 cu yd.
| Where | Depth |
|---|---|
| Topping up last year’s mulch | 1–2 in |
| Flower and shrub beds | 2–3 in |
| Beds with a lot of weeds | 3–4 in |
| Around trees | 2–4 in, kept a few inches away from the trunk |
| Vegetable garden paths | 3–4 in of wood chips or straw |
| Playground surfacing | Often about 12 in, so it stays 9 in or more after settling |
Fresh mulch is fluffy and settles by a fair amount in the first weeks. Many landscapers order for the depth they want after it settles and accept a slightly deeper look on day one.
| Mulch | Good for | Notes |
|---|---|---|
| Shredded hardwood | Beds and borders | Knits together and stays on slopes |
| Pine bark nuggets | Beds, acid-loving plants | Long-lasting, can float away in heavy rain |
| Dyed mulch (black, brown, red) | Strong color | Color fades over a season |
| Cedar and cypress | Beds, paths | Pleasant smell, slow to break down |
| Wood chips (arborist chips) | Paths, tree rings, large areas | Often free or cheap from tree services |
| Pine straw | Beds in the South, slopes | Sold in bales, not by the yard |
| Compost | Vegetable and flower beds | Feeds the soil; breaks down fast |
| Rubber mulch | Play areas | Long-lasting; sold by the bag or by weight |
Bulk mulch is sold by the cubic yard from landscape yards and garden centers. It is usually much cheaper per yard than bags, but most places charge for delivery, so it pays off on bigger jobs. As a rule of thumb, once you need more than about 2–3 yards (27–40 bags of 2 cu ft), get a bulk quote. Enter the price per yard and per bag in the calculator to see the difference.
A 40 × 5 ft foundation bed, two 8 ft round beds and three tree rings 6 ft across (1 ft left bare at each trunk), all 3 in deep: 50 + 25.1 + 20.6 = 95.7 cu ft = 3.54 cu yd. Order 3.5–4 yards in bulk rather than 48 bags.
Measure a slope along the ground, not as it looks from above. A bank 25 ft long and 8 ft from top to bottom along the surface, 3 in deep, needs 25 × 8 × 0.25 = 50 cu ft = 1.85 cu yd. Shredded mulch stays put on slopes better than nuggets.
A 20 × 30 ft play area filled 12 in deep with engineered wood fiber: 20 × 30 × 1 = 600 cu ft = 22.2 cu yd. That is two or three truckloads, so book the delivery early.
Measure the beds, not the lot. Take out the space under shrubs that are already full; mulch under dense shrubs is mostly wasted.
Settling. Fresh shredded mulch can lose a good part of its height as it settles. Quote for the finished depth the customer wants.
Blown mulch. Blower trucks place mulch quickly and evenly; their rates are usually per yard placed. Use the same cubic yard figure.
Keep the list. Add every bed to the project total and save it to the shopping list, so next spring’s top-up is quick to quote.
Multiply the length × width of the bed in feet by the depth in inches ÷ 12 to get cubic feet, then divide by 27 for cubic yards. A 20 × 4 ft bed at 3 in deep needs 20 cu ft, which is 0.74 cubic yards or 10 bags of 2 cu ft.
A cubic yard is 27 cu ft, so it equals 13.5 bags of 2 cu ft, 9 bags of 3 cu ft or 18 bags of 1.5 cu ft.
One cubic yard covers about 162 sq ft at 2 in deep, 108 sq ft at 3 in and 81 sq ft at 4 in.
About 12 sq ft at 2 in deep, 8 sq ft at 3 in or 6 sq ft at 4 in. A 3 cu ft bag covers half as much again: about 12 sq ft at 3 in.
About 2–3 in for most flower and shrub beds, and 3–4 in where weeds are a problem. Topping up an existing bed usually needs only 1–2 in. More than about 4 in can keep water and air from reaching the roots.
No. Keep mulch a few inches away from the trunk and spread it out in a wide, flat ring. Mulch piled up against the bark (a “mulch volcano”) holds moisture against the trunk and can lead to rot and pests.
For more than about 2–3 cubic yards, bulk mulch delivered by the yard is usually cheaper, even with a delivery fee. Bags are handy for small beds, for top-ups and where a truck can’t reach. Enter both prices in the calculator to compare.
Dry wood or bark mulch is roughly 400–800 lb per cubic yard; fresh, wet wood chips can weigh more. That is light enough for a pickup to carry a couple of yards, but check your truck’s payload.
Safety mulch (engineered wood fiber or wood chips) under play equipment is often installed about 12 in deep so it stays at least 9 in deep after it packs down. Follow the CPSC Public Playground Safety Handbook and the equipment maker’s fall-height guidance.
Yes. The CalcWall Mulch Calculator is completely free and works online in any browser, on a phone, tablet or computer. There is nothing to download and no account to create, and the math runs right in your browser, so results appear as you type.