Use this free mulch calculator to find out how many cubic yards or bags of mulch you need for any garden bed, tree ring or landscaping project.
Garden & landscapingMulch Calculator
Bags are rounded up to whole bags. Many suppliers sell bulk mulch in half or whole cubic yards, so round up when ordering.
Our free mulch calculator tells you exactly how much mulch to buy for your garden. First, choose the shape of your bed and enter its size. Then pick a depth, and the calculator shows the cubic yards, cubic feet and number of bags you need. In addition, you can add prices to see whether bags or bulk delivery is cheaper.
How Much Mulch Do I Need?
The amount of mulch you need basically depends on two things: the area you want to cover and how deep you spread it. Because mulch is sold by volume, you need to turn your area and depth into cubic yards or cubic feet. Therefore, the calculator does this conversion for you.
For example, a 100 square foot bed at 3 inches deep needs about 0.93 cubic yards. In other words, that is 13 bags of 2 cubic feet.
How the Mulch Calculator Works
Overall, the calculation has three simple steps. As a result, you can also check the numbers by hand.
First, work out the area in square feet, for example length × width.
Then multiply by the depth in inches and divide by 12 to get cubic feet.
Finally, divide by 27 for cubic yards, or by the bag size for bags.
The formula
Cubic yards = Area (sq ft) × Depth (in) ÷ 324
Mulch Calculator Examples
For example, here are three common garden jobs. In each case, the mulch is spread 3 inches deep.
For instance, a long bed along a fence has an area of 100 square feet.
- First: 100 × 3 ÷ 12 25 cu ft
- Then: 25 ÷ 27 0.93 cu yd
- Finally: 25 ÷ 2 13 bags
When a tree ring has a 3 foot radius, its area is about 28.3 square feet.
- First: 28.3 × 3 ÷ 12 7.07 cu ft
- Then: 7.07 ÷ 27 0.26 cu yd
- Finally: 7.07 ÷ 2 4 bags
When several large beds add up to 1,000 square feet, bulk delivery is usually cheaper.
- First: 1,000 × 3 ÷ 12 250 cu ft
- Then: 250 ÷ 27 9.26 cu yd
- Alternatively, in bags 125 bags
Mulch Coverage Chart
Alternatively, use this chart for a quick estimate. In each cell, bags are 2 cubic feet and rounded up.
| Area | 2 inches deep | 3 inches deep | 4 inches deep |
|---|---|---|---|
| 50 sq ft | 0.31 yd (5 bags) | 0.46 yd (7 bags) | 0.62 yd (9 bags) |
| 100 sq ft | 0.62 yd (9 bags) | 0.93 yd (13 bags) | 1.23 yd (17 bags) |
| 200 sq ft | 1.23 yd (17 bags) | 1.85 yd (25 bags) | 2.47 yd (34 bags) |
| 500 sq ft | 3.09 yd (42 bags) | 4.63 yd (63 bags) | 6.17 yd (84 bags) |
| 1,000 sq ft | 6.17 yd (84 bags) | 9.26 yd (125 bags) | 12.35 yd (167 bags) |
Here, yd means cubic yards. Also, one cubic yard covers about 108 square feet at 3 inches deep.
How Deep Should Mulch Be?
According to the University of Illinois Extension, 2 to 4 inches of mulch is generally right for most trees and beds.
- Fine mulch: compost and fine bark work best at 2 to 3 inches, because they pack down tightly.
- Coarse mulch: in contrast, wood chips and large bark can go to 3 to 4 inches.
- Around trees: keep mulch at least 4 inches away from the trunk, because mulch touching the bark can cause rot and attract pests.
- Avoid mulch volcanoes: piling mulch high against a tree traps moisture against the bark, so spread it flat instead.
Bags or Bulk Mulch?
Bagged mulch is easy to carry and store, so it suits small beds and touch-ups. However, bulk mulch is usually cheaper per cubic yard for bigger jobs, even after a delivery fee. To compare, enter both prices in the calculator. Then it shows which option costs less for your project.
How to Use the Mulch Calculator
- First, choose the shape of your bed or tree ring.
- Next, enter the measurements in feet.
- Then set the depth in inches, since most beds need 3 inches.
- After that, pick your bag size and add prices if you want a cost estimate.
- Finally, press Calculate Mulch to see the cubic yards and bags you need.
More Home and Garden Calculators
These tools also help with projects around the house. Alternatively, browse all our construction calculators.
Mulch Calculator FAQs
How much mulch do I need?
First, measure the area in square feet. Then multiply it by the depth in inches and divide by 324 to get cubic yards. For example, a 100 square foot bed at 3 inches needs about 0.93 cubic yards.
How many bags of mulch are in a cubic yard?
First, remember that a cubic yard is 27 cubic feet. Therefore, it equals about 13.5 bags of 2 cubic feet, 18 bags of 1.5 cubic feet or 9 bags of 3 cubic feet.
How deep should mulch be?
Generally, most beds and trees need 2 to 4 inches of mulch. However, fine mulch such as compost works best at 2 to 3 inches, while coarse wood chips can go to 3 to 4 inches.
How much area does a bag of mulch cover?
For example, a 2 cubic foot bag covers about 8 square feet at 3 inches deep. In other words, it covers 24 square feet at 1 inch or 12 square feet at 2 inches.
Is it cheaper to buy mulch in bags or bulk?
Bags are handy for small jobs because they are easy to carry. However, bulk mulch is usually cheaper per cubic yard for larger areas, even after delivery fees. Therefore, enter both prices in the calculator to compare.
Can I use this mulch calculator for rocks or rubber mulch?
Yes, because the volume is the same for any material, so the cubic yards and cubic feet are correct. Even so, rocks and rubber are sold by weight or by different bag sizes, so check your supplier's coverage chart.
Disclaimer: This calculator gives an estimate for general information only. Mulch settles over time, so many gardeners buy 5 to 10% extra. Moreover, bag sizes and coverage vary by brand, so check the label before you buy.