Mulch Calculator
This mulch calculator tells you how much mulch a bed, border or tree ring needs. Enter the size as a rectangle, a circle or a total area, set the depth, and you get the cubic yards to order in bulk and the number of 2 or 3 cu ft bags. It also flags whether your depth falls inside the 2 to 4 in range extension services recommend.
Updated
Results
- Volume (cu ft)
- Area (sq ft)
- Depth checkCompared with the 2–4 in range
- Cost in bulkShown when you enter a price per cubic yard
- Cost in bagsShown when you enter a price per bag
Results are estimates. See the methodology below.
How to use the mulch calculator
- Pick the shape: Rectangle for beds and borders, Circle for a ring around a tree, or Known area if you have already added up several beds.
- Enter the depth you want once the mulch is spread. Topping up an old layer? Measure what is left and enter only the difference.
- Choose the bag size printed on the bags you plan to buy: 2 cu ft or 3 cu ft.
- In Advanced options, add an extra percentage if you want a margin for uneven ground or settling.
- Optionally enter a bulk price per cubic yard and a price per bag to compare both ways of buying.
How the calculator works
- Area = length × width, or π × (diameter ÷ 2)² for a circle
- Cubic feet = area × depth ÷ 12 × (1 + extra %)
- Cubic yards = cubic feet ÷ 27
- Bags = cubic feet ÷ bag size, rounded up
A cubic yard is 27 cu ft, so it equals 13.5 bags of 2 cu ft or 9 bags of 3 cu ft. At 3 in deep, one cubic yard covers 108 sq ft.
The depth check
The University of Illinois Extension recommends a mulch layer of 2 to 4 in: 2 to 3 in for composted materials and 3 to 4 in for coarse mulches such as bark or wood chips. The calculator labels anything under 2 in as below and anything over 4 in as above that range. The extra percentage starts at 0; it is your own allowance, not a standard figure.
Worked examples
Front bed, 20 × 10 ft at 3 in
200 sq ft at 3 in is 50.0 cu ft, or 1.85 cubic yards. Bagged, that is 25 bags of 2 cu ft or 17 bags of 3 cu ft.
Tree ring, 8 ft across at 3 in
The circle covers 50.3 sq ft and needs 12.6 cu ft, about 0.47 cubic yards: 7 bags of 2 cu ft or 5 bags of 3 cu ft. Keep the mulch pulled back from the trunk.
Several beds totaling 600 sq ft
| Depth | Cubic yards | 2 cu ft bags |
|---|---|---|
| 2 in | 3.70 | 50 |
| 3 in | 5.56 | 75 |
| 4 in | 7.41 | 100 |
Each extra inch adds almost 2 cubic yards here, which is why measuring the depth you really need matters.
Topping up a border
A 30 × 4 ft border has 1 in of old mulch and you want 3 in. Enter 2 in: 0.74 cubic yards, or 10 bags of 2 cu ft, instead of the 15 bags a full 3 in layer would take. Planning a fence around the beds? Our fence calculator counts posts and concrete.
Frequently asked questions
How many bags of mulch are in a yard?
A cubic yard holds 27 cu ft, so it equals 13.5 bags of 2 cu ft or 9 bags of 3 cu ft. The calculator rounds up to whole bags.
How much area does a yard of mulch cover?
At 3 in deep, one cubic yard covers 108 sq ft. At 2 in it stretches further, at 4 in it covers less. Enter your depth and area to see the exact volume.
How deep should mulch be?
University of Illinois Extension recommends 2 to 4 in: 2 to 3 in for composted material and 3 to 4 in for coarse mulch. It also advises keeping mulch at least 4 in away from tree trunks.
Can I pile mulch around a tree trunk?
No. Mississippi State University Extension warns against mulch volcanoes and says not to let mulch touch the trunk. Spread a flat layer instead; Illinois Extension suggests extending it toward the dripline.
Is bulk mulch cheaper than bags?
Often for big jobs, but it depends on local prices and delivery fees. Enter a price per cubic yard and a price per bag and compare the two cost lines.
What if I use gravel or rock instead of mulch?
Stone is sold by weight as well as volume. Use our gravel calculator, which adds tons and 50 lb bags to the cubic yards.
Sources
This is a volume estimate based on the dimensions and depth you enter. Bag sizes and bulk measures vary by supplier, so check the label or quote before you buy.