Mulch Calculator
Work out how much mulch to buy for flower beds, shrub borders and tree rings. Enter the size of each bed and the depth you want, and this mulch calculator shows the cubic yards to order in bulk and the number of 1.5, 2 or 3 cu ft bags to buy.
Your results will appear here.
How to use the mulch calculator
- Choose the bed shape. Use “Circle” for a ring around a tree. For a long, curved border, measure it as a rectangle using its average width.
- Enter the measurements in feet, or the area if you know it.
- Choose the depth. Most beds need 2 to 3 in of new mulch. If an older layer is still there, you may only need 1 in to top it up.
- Add a small extra allowance for uneven ground and edges. About 5% is usually enough.
- Pick a bag size and enter the price per bag to see the cost.
Mulch formula
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 bed measures 20 ft by 10 ft. You want 3 in of mulch with 5% extra and plan to buy 2 cu ft bags:
- Area: 20 × 10 = 200 sq ft
- Volume: 200 × 3 ÷ 12 = 50 cu ft, plus 5% = 52.5 cu ft
- Cubic yards: 52.5 ÷ 27 = 1.94 cu yd, or about 2 yards in bulk
- Bags: 52.5 ÷ 2 = 26.25, rounded up to 27 bags
For a tree ring 6 ft across at 3 in deep, the area is 3.1416 × 3 × 3 = 28.3 sq ft, which needs about 7.1 cu ft of mulch, or 4 bags of 2 cu ft.
Mulch coverage chart
| 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 deep should mulch be?
University of Nebraska–Lincoln Extension recommends an even layer of 2 to 4 in around trees and shrubs and a thinner layer of 1 to 2 in around smaller plants such as annuals and perennials. Deeper is not better: more than about 4 in can keep water and air from reaching the roots.
Tips for mulching beds
- Keep mulch off trunks and stems. Leave a few inches of bare ground around the base of trees and shrubs. Mulch piled against bark holds moisture and invites rot and pests.
- Check what is already there. Old mulch breaks down slowly. Rake it loose and measure it before you buy, so you only add what you need.
- Weed and water first. Pull weeds and water the bed before you spread mulch. Mulch is good at holding moisture in, but it can also keep light rain out of dry soil.
- Buy in bulk for big jobs. About 13 bags of 2 cu ft equal one cubic yard. For a few yards or more, bulk mulch is usually much cheaper per yard than bags.
Frequently asked questions
How many bags of mulch are in a yard?
One cubic yard is 27 cubic feet. That equals 18 bags of 1.5 cu ft, 13.5 bags of 2 cu ft or 9 bags of 3 cu ft.
How much area does a yard of mulch cover?
A cubic yard covers about 324 sq ft at 1 in deep, 162 sq ft at 2 in, 108 sq ft at 3 in and 81 sq ft at 4 in.
How much mulch do I need for a 10 x 10 bed?
A 10 x 10 ft bed is 100 sq ft. At 3 in deep it needs 25 cu ft of mulch, which is about 0.93 cubic yards or 13 bags of 2 cu ft.
How deep should mulch be around trees?
Spread 2 to 4 in of mulch in a wide ring around trees, but keep it a few inches away from the trunk. Never pile mulch up against the bark.
Do I need to remove old mulch before adding new?
Usually not. If the old layer is loose and less than a couple of inches deep, rake it and add a fresh layer on top. Remove it only if it has matted into a crust or the total depth would be more than about 4 in.
Sources and methodology
The formulas on this page were written and checked by the HomeQuantly Team against the worked examples shown above. Results are estimates for planning; always confirm measurements on site before you buy materials.