Mulch Calculator
Enter the size of your garden bed and how deep you want the mulch to get the cubic yards for a bulk order, or how many bags to buy.
Mulch for common bed sizes
| Bed | Area | 2 in deep | 3 in deep | 2 cu ft bags at 3 in |
|---|---|---|---|---|
| 4 × 8 ft | 32 sq ft | 0.20 yd³ | 0.30 yd³ | 4 |
| 3 × 20 ft | 60 sq ft | 0.37 yd³ | 0.56 yd³ | 8 |
| 5 × 10 ft | 50 sq ft | 0.31 yd³ | 0.46 yd³ | 7 |
| 10 × 10 ft | 100 sq ft | 0.62 yd³ | 0.93 yd³ | 13 |
| 4 × 25 ft | 100 sq ft | 0.62 yd³ | 0.93 yd³ | 13 |
| 10 × 20 ft | 200 sq ft | 1.23 yd³ | 1.85 yd³ | 25 |
| 20 × 20 ft | 400 sq ft | 2.47 yd³ | 3.70 yd³ | 50 |
| 25 × 40 ft | 1000 sq ft | 6.17 yd³ | 9.26 yd³ | 125 |
How much area a yard of mulch covers
| Depth | 1 cubic yard covers | One 2 cu ft bag 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 |
How to calculate mulch
- Find the area in square feet. Rectangle: length × width. Circle: 3.1416 × radius². Odd shapes: split them into rectangles and circles and add them up.
- Multiply by the depth in inches, then divide by 12 to get cubic feet. 100 sq ft × 3 in ÷ 12 = 25 cu ft.
- Divide by 27 for cubic yards (bulk mulch), or by the bag size for bags. 25 ÷ 27 = 0.93 yd³; 25 ÷ 2 = 13 bags.
Measure your beds with a tape measure. Long, curving beds are easiest to measure as a length along the middle times the average width.
How deep to spread mulch
| Where | Depth |
|---|---|
| Flower beds and annuals | 2 in |
| Shrub beds and perennials | 2–3 in |
| Around trees | 2–4 in, in a wide ring, kept 3–6 in off the trunk |
| Paths and weed control | 3–4 in |
| Yearly top-up | About 1 in |
Fine shredded mulch packs down and needs less depth; coarse wood chips and bark nuggets settle less and can go a little deeper. For playground surfacing, follow the depth the equipment maker or the CPSC Public Playground Safety Handbook gives for the fall height.
Frequently asked questions
How much mulch do I need for 100 square feet?
At 3 inches deep, 100 sq ft needs 25 cubic feet of mulch: about 0.93 cubic yard, or 13 bags of 2 cu ft. At 2 inches deep it's 16.7 cu ft, or 9 bags.
How much does a yard of mulch cover?
One cubic yard covers 324 square feet 1 inch deep, so 162 sq ft at 2 inches, 108 sq ft at 3 inches and 81 sq ft at 4 inches.
How many bags of mulch are in a yard?
13.5 bags of 2 cubic feet, 9 bags of 3 cu ft or 18 bags of 1.5 cu ft, since a cubic yard is 27 cubic feet. For more than 2 or 3 yards, bulk mulch delivered by the yard is usually much cheaper than bags.
How deep should mulch be?
2 to 3 inches for most flower and shrub beds, and 3 to 4 inches where you want to smother weeds. More than 4 inches can keep water and air from the roots. Keep mulch 3 to 6 inches away from tree trunks and plant stems instead of piling it against them.
How often should I add mulch?
Organic mulch breaks down, so most beds need a 1 inch top-up every year, usually in spring. Check the depth first: if the old layer is still 2 to 3 inches, rake it to refresh the color instead of adding more.
Laying a path or patio base instead? Use the gravel calculator. Pouring a pad? The concrete calculator works out the bags.