Mulch Calculator
Measure the bed, choose how deep the mulch should be, and the calculator shows the volume you need. Tell it the bag size and it counts the bags and prices them against a bulk delivery.
Created by the Reeliy Editorial Team. Last updated: Oct 19, 2026
How to use the mulch calculator
- Pick US units or Metric units, then say whether the bed is rectangular or circular.
- Enter the width and length, or the diameter, and the depth you plan to spread. Each value can use its own unit.
- Choose In Bags if you will buy bagged mulch, and type the bag size using cubic feet, cubic meters or liters. Choose In Bulk to buy by the cubic yard or cubic meter.
- Add a price per bag, or per cubic yard or meter for bulk, to get the cost.
Without a bag size the result shows only the volume, and a price on its own is ignored in bag mode because the cost depends on how many bags you buy.
Calculating the volume of mulch
rectangular bed: volume = width × length × depth
round bed: volume = π × (diameter ÷ 2)2 × depth
bags = volume ÷ volume per bag
Convert the depth to the same unit as the footprint before multiplying, or let the calculator do it. A common slip is to treat 3 inches as 3 feet and end up ordering twelve times too much.
Example: a rectangular border
A border 12 ft long and 4 ft wide, mulched 3 inches deep, needs 12 × 4 × 0.25 = 12 ft3, which is 0.444 yd3. With 2 cu ft bags that is exactly 6 bags. At $4.50 a bag the total is $27.
Example: a round tree ring
A ring 5 ft across with 2 inches of mulch holds π × 2.52 × (2/12) = 3.27 ft3. That is 1.64 bags of 2 cu ft, so you would buy two and have a little left. The calculator reports the fraction so you can see how close you are to the next whole bag.
Example in metric units
A bed of 8 m by 1.5 m covered with 7 cm of mulch is 8 × 1.5 × 0.07 = 0.84 m3, or 840 liters. With 50 liter bags that is 16.8, so buy 17.
Irregular beds
Split the bed into rectangles and circles, calculate each part, and add the volumes. For a free-form bed, sketch it on graph paper, count the squares and treat that area as a rectangle of the same size.
How much area does mulch cover?
A cubic yard is 27 ft3. Divide 324 by the depth in inches to get the area in square feet that one cubic yard covers.
| Depth | One cubic yard covers | One 2 cu ft bag covers |
|---|---|---|
| 1 inch | 324 ft2 | 24 ft2 |
| 2 inches | 162 ft2 | 12 ft2 |
| 3 inches | 108 ft2 | 8 ft2 |
| 4 inches | 81 ft2 | 6 ft2 |
Most gardeners aim for 2 to 3 inches of wood mulch. Less lets weeds through; much more can hold too much moisture against plant stems and trunks. Keep a gap around stems rather than piling mulch against them.
Bag sizes and bags per cubic yard
Bagged mulch is usually labelled by volume. The number of bags in a cubic yard follows from 27 ÷ bag size:
| Bag size | Bags per cubic yard | Bags per cubic meter |
|---|---|---|
| 1 cu ft | 27 | 35.3 |
| 1.5 cu ft | 18 | 23.5 |
| 2 cu ft | 13.5 | 17.7 |
| 3 cu ft | 9 | 11.8 |
Bag labels are sometimes rounded, and the mulch settles in transit, so the bags may hold slightly less than printed.
Wood mulch compared with rubber mulch
| Wood and bark mulch | Rubber mulch | |
|---|---|---|
| Price per volume | Lower | Higher |
| Lifespan | Breaks down within a year or two and needs topping up | Lasts many years without breaking down |
| Effect on soil | Feeds the soil as it decomposes | Adds no nutrients |
| Weight | Light when dry | Heavier per cubic foot |
| Typical use | Garden beds, trees, borders | Playgrounds and paths where cushioning matters |
The calculator measures volume, which is the same for any material, so the quantity for rubber and wood mulch is the same. Only the price and the weight differ.
Buying in bulk or in bags
Bags are easy to carry and store, but the price per cubic yard is usually higher. A 2 cu ft bag at $4.50 works out to 13.5 × $4.50 = $60.75 per cubic yard, which is the figure the calculator prints beside the cost. Compare that with the delivered price of a bulk load. Bulk typically wins above one or two cubic yards, if you have a place to drop the pile and a way to move it.
These quantities are estimates for shopping. Settling, uneven ground and the shape of the bed change the real amount. See the disclaimer. Related materials: soil, gravel and sand.
Frequently asked questions
How many bags of mulch are in a cubic yard?
Divide 27 by the bag size in cubic feet: 13.5 bags of 2 cu ft, 18 bags of 1.5 cu ft, 9 bags of 3 cu ft or 27 bags of 1 cu ft.
How deep should mulch be?
Two to three inches (5 to 8 cm) is the usual range for wood mulch around plants. Thinner layers are less effective against weeds, and thicker ones can smother roots.
How much area does a cubic yard of mulch cover?
At 2 inches deep it covers 162 square feet, at 3 inches 108 square feet. In metric units one cubic meter covers 10 m2 at 10 cm deep.
Is it cheaper to buy mulch in bulk?
Usually, once you need more than a cubic yard or two. Convert the bag price to a price per cubic yard (bag price × 27 ÷ bag size in cu ft) and compare it with the delivered bulk price, including any delivery fee.
Cite this calculator and page
If you use this page in your work, you can cite it as:
Reeliy Editorial Team. (2026). Mulch Calculator. Reeliy. https://reeliy.com/calculators/mulch-calculator“Mulch Calculator.” Reeliy, 2026, https://reeliy.com/calculators/mulch-calculator.