🪵 Mulch Calculator
By ToolNimba Editorial Team · Updated 2026-06-19
The calculator multiplies the bed area by the depth to get loose volume, then converts to cubic yards by dividing by 27 and to bags using your bag size (default 2 cubic feet). Bags are rounded up to the nearest whole bag. Areas entered in meters are converted to square feet before the volume is worked out. This is loose, settled mulch, order a little extra for spillage and to top up as it breaks down.
This mulch calculator tells you how much mulch to buy for a garden bed at the depth you want. Enter the bed length and width (or a total area you already know) and the depth in inches, and it returns the volume in cubic yards and cubic feet, plus the number of standard bags. You can work in feet or meters, so there is no guesswork at the garden center or when ordering a bulk load.
What is the Mulch Calculator?
Mulch is sold two ways: in bags (commonly 2 cubic feet each) for small jobs, or loose by the cubic yard for larger beds, delivered or scooped at a landscape yard. To work out how much you need you only have to know two things: the area you are covering and how deep you want the layer. Multiply the area in square feet by the depth in feet and you have the volume in cubic feet. Divide that by 27 (there are 27 cubic feet in a cubic yard) to get cubic yards, the unit bulk mulch is priced in.
The depth is the part people get wrong most often. A typical mulch layer is 2 to 4 inches deep: around 2 to 3 inches for flower and vegetable beds, and 3 to 4 inches around trees and shrubs where you want stronger weed suppression and moisture retention. Going much deeper than 4 inches can smother roots and hold too much moisture against stems, so more is not always better. Because depth is measured in inches but area in feet, the calculator converts the depth to feet (inches divided by 12) before working out the volume.
A quick reality check helps: one cubic yard of mulch covers about 100 square feet at 3 inches deep, or roughly 160 square feet at 2 inches. So a yard is enough for a modestly sized bed, and a single 2 cubic foot bag covers only about 8 square feet at 3 inches, which is why bagged mulch gets expensive fast on bigger projects. Order a little extra for spillage, uneven ground, and to top up later, since organic mulch breaks down and settles over a season.
When to use it
- Working out how many bags of mulch to buy for a flower or vegetable bed before a trip to the garden center.
- Deciding whether to buy bags or order a bulk cubic-yard load by comparing the volume each option covers.
- Estimating mulch for a ring around trees and shrubs at a 3 to 4 inch depth.
- Budgeting a landscaping job by converting bed dimensions into cubic yards to price against a supplier rate.
How to use the Mulch Calculator
- Choose your units (feet or meters) and whether you want to enter length x width or a total area.
- Enter the bed dimensions, or the total area if you already know it.
- Set the desired mulch depth in inches (2 to 4 inches is typical).
- Adjust the bag size if your bags are not the standard 2 cubic feet.
- Read off the cubic yards, cubic feet, and number of bags you need.
Formula & method
Worked examples
A bed 20 ft long by 10 ft wide, mulched 3 inches deep, using 2 cubic foot bags.
- Area = 20 x 10 = 200 sq ft
- Depth in feet = 3 / 12 = 0.25 ft
- Volume = 200 x 0.25 = 50 cubic feet
- Cubic yards = 50 / 27 = 1.85 cu yd
- Bags = round up of (50 / 2) = round up of 25 = 25 bags
Result: 50 cu ft, about 1.85 cu yd, or 25 bags
A bed 12 ft by 8 ft, mulched 2 inches deep, using 2 cubic foot bags.
- Area = 12 x 8 = 96 sq ft
- Depth in feet = 2 / 12 = 0.1667 ft
- Volume = 96 x 0.1667 = 16 cubic feet
- Cubic yards = 16 / 27 = 0.59 cu yd
- Bags = round up of (16 / 2) = round up of 8 = 8 bags
Result: 16 cu ft, about 0.59 cu yd, or 8 bags
Mulch needed to cover 100 square feet at common depths (2 cubic foot bags)
| Depth | Cubic feet | Cubic yards | Bags (2 cu ft) |
|---|---|---|---|
| 1 inch | 8.33 | 0.31 | 5 |
| 2 inches | 16.67 | 0.62 | 9 |
| 3 inches | 25.00 | 0.93 | 13 |
| 4 inches | 33.33 | 1.23 | 17 |
Roughly how much area one cubic yard of mulch covers by depth
| Depth | Coverage from 1 cubic yard |
|---|---|
| 1 inch | about 324 sq ft |
| 2 inches | about 162 sq ft |
| 3 inches | about 108 sq ft |
| 4 inches | about 81 sq ft |
Common mistakes to avoid
- Forgetting to convert depth from inches to feet. Area is in square feet but depth is usually given in inches. If you multiply square feet by inches you get a number that is 12 times too large. Always divide the depth in inches by 12 first, so 3 inches becomes 0.25 feet.
- Mulching too deep. Piling mulch more than about 4 inches deep, or heaping it against trunks and stems, can suffocate roots and trap moisture that rots the plant. A 2 to 4 inch layer is plenty for most beds.
- Mixing up cubic feet and cubic yards. Bagged mulch is measured in cubic feet, bulk mulch in cubic yards, and there are 27 cubic feet in a yard. Ordering yards when you meant feet (or the reverse) can leave you 27 times short or long.
- Not ordering a little extra. Beds are rarely perfect rectangles, ground is uneven, and some mulch is lost to spillage. Adding around 5 to 10 percent avoids a second trip, and a small surplus is handy for topping up as mulch settles.
Glossary
- Mulch
- A layer of material such as bark, wood chips, straw or compost spread over soil to retain moisture, suppress weeds and protect roots.
- Cubic foot
- A volume one foot wide, one foot deep and one foot tall. The unit bagged mulch is sold in, commonly 2 cubic feet per bag.
- Cubic yard
- A volume three feet on each side, equal to 27 cubic feet. The unit bulk mulch is priced and delivered in.
- Depth
- How thick the mulch layer is, usually measured in inches. Typical depths run from 2 to 4 inches.
- Coverage
- The floor area a given volume of mulch will cover at a chosen depth, for example one cubic yard covers about 108 square feet at 3 inches.
Frequently asked questions
How much mulch do I need?
Multiply the area you are covering in square feet by the depth in feet (depth in inches divided by 12) to get the volume in cubic feet, then divide by 27 for cubic yards. For example, a 200 square foot bed at 3 inches deep needs 50 cubic feet, about 1.85 cubic yards, or 25 standard 2 cubic foot bags.
How many bags of mulch are in a cubic yard?
There are 27 cubic feet in a cubic yard, so with standard 2 cubic foot bags you need 13.5 bags to equal one yard, which rounds up to 14 bags. With 3 cubic foot bags it is 9 bags per yard.
How deep should mulch be?
A layer of 2 to 4 inches works for most situations: around 2 to 3 inches for flower and vegetable beds, and 3 to 4 inches around trees and shrubs for stronger weed control. Avoid going much deeper than 4 inches or piling mulch against stems.
How much area does a cubic yard of mulch cover?
One cubic yard covers about 324 square feet at 1 inch, 162 square feet at 2 inches, 108 square feet at 3 inches, and 81 square feet at 4 inches deep. Deeper layers cover less area from the same volume.
Should I buy mulch in bags or in bulk?
Bags are convenient for small beds and easy to carry, but cost more per cubic foot. For larger areas, bulk mulch ordered by the cubic yard is usually cheaper, though you need a way to haul or have it delivered and a spot to dump it.
Does this calculator work in meters?
Yes. Switch the units to meters and enter your bed in meters or square meters. The calculator converts the area to square feet (1 square meter is about 10.76 square feet) before working out the volume in cubic feet, cubic yards and bags.