CalcWoven • Mulch Calculator
Mulch Calculator
Enter your bed size and depth to get cubic yards, bags and weight of mulch, plus an estimated cost. There is a tree ring option too. Free, with no sign-up.
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Bed size and depth
Keep mulch off the trunk. Penn State Extension suggests pulling mulch 3 to 5 inches away from young trees and 8 to 10 inches from mature trees.
Extension sources recommend about 2 to 4 inches: finer mulches toward 2, coarse wood chips toward 4. Check any mulch already in place and order only the difference.
Mulch weight
About 500 lb per cubic yard, the planning figure used across CalcWoven. Dry wood or bark mulch commonly falls in a 400–800 lb range.
Bags and cost (optional)
Many bagged mulches are 2 or 3 cu ft. Check the volume printed on your bag.
You need
- Area—
- Cubic feet—
- Cubic meters—
- Bags needed—
- Estimated weight—
- One cubic yard covers—
- Estimated cost—
Results update as you type.
Formula: area × depth ÷ 12 = cubic feet; ÷ 27 = cubic yards.
HOW IT WORKS
From bed size and depth to cubic yards
The calculator multiplies the bed area by the mulch depth to get cubic feet, then divides by 27 to get cubic yards. In one step, cubic yards = square feet × depth in inches ÷ 324. For example, a 20 × 10 ft bed at 3 inches deep is 200 × 3 ÷ 324 = 1.85 cubic yards, which is 50 cubic feet or 25 bags of 2 cu ft.
How deep should mulch be?
Iowa State Extension says 2 to 4 inches is generally effective, with coarser mulches such as wood chips on the higher end and finer mulches on the lower end, and that shredded bark is best at 2 to 3 inches. University of Illinois Extension also recommends 2 to 4 inches and warns that thick layers can become matted, reducing water and oxygen reaching the soil.
| Depth | One cubic yard covers | Cubic yards per 100 sq ft | Bags of 2 cu ft per 100 sq ft | Bags of 3 cu ft per 100 sq ft |
|---|---|---|---|---|
| 2 inches | 162 sq ft | 0.62 | 9 | 6 |
| 3 inches | 108 sq ft | 0.93 | 13 | 9 |
| 4 inches | 81 sq ft | 1.23 | 17 | 12 |
Mulch needed for common bed sizes
| Bed area | 2 inches deep | 3 inches deep | 4 inches deep |
|---|---|---|---|
| 50 sq ft | 0.31 | 0.46 | 0.62 |
| 100 sq ft | 0.62 | 0.93 | 1.23 |
| 200 sq ft | 1.23 | 1.85 | 2.47 |
| 500 sq ft | 3.09 | 4.63 | 6.17 |
Figures are cubic yards before any extra allowance.
Mulching around trees
Use the Tree ring option to work out the area between the trunk gap and the outer edge of the ring. Penn State Extension says to keep all mulch away from the trunk, to pull it 3 to 5 inches away from young trees and 8 to 10 inches from mature trees, to keep the depth no more than 4 inches, and that “volcano” mulching is never recommended. A 6 ft ring with a 1 ft clear space at 3 inches deep needs about 0.25 cubic yards, or 4 bags of 2 cu ft.
Check what is already there
NC State Extension advises measuring how much mulch is already in the bed before topping up, and University of Illinois Extension says to wait to replenish until the old mulch has decomposed. Enter only the depth you need to add.
Bags or bulk?
A cubic yard is 27 cubic feet, so it takes 13.5 bags of 2 cu ft (buy 14) or 9 bags of 3 cu ft. For bag counts and prices, bulk is usually cheaper at larger volumes, so compare both. See how many bags of mulch are in a cubic yard.
How much does mulch weigh?
The calculator uses about 500 lb per cubic yard for dry wood or bark mulch, and about 1,000 lb for very wet mulch. Real weight depends on the material and how much water it holds, so confirm with your supplier before hauling. See how much does a yard of mulch weigh.
Sources
QUICK ANSWERS
Common questions
How many cubic yards of mulch do I need?
Multiply the area in square feet by the depth in inches, then divide by 324. For example, 1,000 sq ft at 3 inches is 1,000 × 3 ÷ 324 = 9.26 cubic yards.
How much mulch do I need for 100 square feet?
At 3 inches deep, about 0.93 cubic yards, which is 25 cubic feet or 13 bags of 2 cu ft. At 2 inches it is 0.62 cubic yards, and at 4 inches 1.23.
How many bags of mulch are in a cubic yard?
13.5 bags of 2 cu ft, or 9 bags of 3 cu ft. Round up to whole bags when you buy.
How deep should I put mulch?
Extension sources give 2 to 4 inches, with finer mulch toward the thin end and coarse wood chips toward the thick end. Deeper layers can block air and water from reaching the soil.
Should I order extra mulch?
A small allowance can help with uneven ground or a heavier hand. Use the extra selector to include 5 to 15%. The default is 0%, so the main result reflects only your measurements.
Does this calculator know mulch prices?
No. Prices vary by supplier, region and mulch type. Enter your own price per cubic yard or per bag for a cost estimate.
MORE TOOLS
Working on the rest of the garden?
Use the Topsoil Calculator for new beds, the Cubic Yards Calculator for gravel or sand, or the Gravel Calculator for paths. For the math behind the conversion, see square feet to cubic yards. Questions about this tool? See the FAQ.
Weights and depths are planning estimates and vary by mulch type, moisture and site. This calculator gives a general estimate based on the measurements you enter. Results are for reference only.