How much mulch do I need?
Measure the length and width of each bed, decide how deep you want the mulch, and enter the numbers above. The calculator gives you the volume in cubic yards. Bulk mulch is delivered by the cubic yard, and bagged mulch is sold in cubic feet.
Recommended mulch depth
| Where | Typical depth |
|---|---|
| Flower beds | 2 to 3 inches |
| Around trees and shrubs | 2 to 4 inches, kept away from the trunk |
| Vegetable garden | 2 to 3 inches |
| Play areas (wood chips) | Often 6 to 12 inches, check local guidance |
Too little mulch lets weeds through and dries out quickly. Too much can hold moisture against stems and trunks. Pull mulch back a few inches from tree trunks and plant stems.
Quick formula: cubic yards = length (ft) × width (ft) × depth (in) ÷ 324. For example, a 10 ft × 10 ft area at 3 inches deep is 10 × 10 × 3 ÷ 324 = 0.93 cubic yards. The calculator above does this for you and adds the waste allowance.
Bagged mulch or bulk?
A standard bag is often 2 cubic feet, so it takes about 13.5 bags to make a cubic yard. Bagged mulch suits small jobs and is easy to carry. Bulk delivery is usually cheaper per cubic foot once you need around 3 cubic yards or more, but compare local prices and delivery fees.
Worked examples
One flower bed. A bed 20 ft long, 5 ft wide and 3 inches deep holds 25 cubic feet, which is 0.93 cubic yards. That is about 12.5 bags of 2 cubic feet each.
Whole garden refresh. 600 square feet of beds at 2 inches deep is 100 cubic feet, or 3.7 cubic yards. Adding 5% waste makes it about 3.9 cubic yards.
Tree ring. A circle 6 ft across at 3 inches deep is about 7.1 cubic feet, or 0.26 cubic yards.
How far does a cubic yard of mulch go?
| Depth | Area covered by 1 cubic yard | Cubic yards for 100 sq ft |
|---|---|---|
| 1 inch | 324 sq ft | 0.31 |
| 2 inches | 162 sq ft | 0.62 |
| 3 inches | 108 sq ft | 0.93 |
| 4 inches | 81 sq ft | 1.23 |
| 6 inches | 54 sq ft | 1.85 |
| 12 inches | 27 sq ft | 3.70 |
Tips for buying mulch
- Fresh mulch needs a lighter top-up each year rather than a full new layer. Measure what is left before you buy.
- Rake the old mulch to loosen it first. Compacted mulch can be reused.
- Weight varies a great deal with moisture. Wet mulch can be much heavier than dry, so volume is the safer way to order.
- Check that dyed or coloured mulch is suitable for edible gardens if that matters to you.
Frequently asked questions
How many bags of mulch make a cubic yard? About 13.5 bags if each bag is 2 cubic feet. Check the bag size, because some are smaller or larger.
How many square feet does a cubic yard of mulch cover? About 108 square feet at 3 inches deep, 162 at 2 inches, and 81 at 4 inches.
How much does a cubic yard of mulch weigh? Often somewhere between 0.25 and 0.5 tons, depending on the type and how wet it is. The calculator uses an estimate of 0.4 tons.
How often should I replace mulch? Many gardeners top up once a year or every two years, depending on how fast it breaks down.