Mulch Calculator
Find out how much mulch you need. Enter your bed's length, width, and depth and this mulch calculator gives you the cubic yards, cubic feet, and number of bags.
Reviewed & updated for 2026 by Rakesh Choudhary, PhDMethodology & sources · How we calculate
How deep should mulch be?
Depth drives how much you buy. University of Maryland Extension advises keeping mulch shallow, one to three inches depending on the material, and keeping it about 3 inches away from the base of tree trunks; too much mulch can harm the plants it is meant to protect (Mulching Trees and Shrubs).
Organic mulch also settles and decomposes, so beds need topping up. Check the depth before adding more, rather than piling a fresh full layer on top of the old one.
Coverage per cubic yard
| Depth | 1 cubic yard covers | 2 cu ft bags / yard |
|---|---|---|
| 1 inch | 324 sq ft | 13.5 |
| 2 inches | 162 sq ft | 13.5 |
| 3 inches | 108 sq ft | 13.5 |
| 4 inches | 81 sq ft | 13.5 |
A cubic yard is always 13.5 bags (2 cu ft) regardless of depth; only the area it covers changes.
Mulch needed for common bed sizes
A starting point for a 3-inch layer, the top of the extension range. Bags assume the common 2-cubic-foot size (one bag covers about 8 sq ft at 3 inches deep). Bulk mulch is sold by the cubic yard, which covers 108 sq ft at the same depth:
| Bed size | Cubic yards (3" deep) | 2 cu ft bags |
|---|---|---|
| 50 sq ft | 0.5 | 7 |
| 100 sq ft | 0.9 | 13 |
| 200 sq ft | 1.9 | 25 |
| 300 sq ft | 2.8 | 38 |
| 500 sq ft | 4.6 | 63 |
| 1,000 sq ft | 9.3 | 125 |
For a 2-inch layer, multiply these amounts by ⅔; for 1 inch, by ⅓. The calculator above does the exact math for your bed shape and depth.
FAQs
How much mulch do I need?
Work out the bed's area in square feet, multiply it by the depth converted to feet, and divide by 27 to turn cubic feet into cubic yards. For a bed 20 feet long and 10 feet wide at 3 inches, that is 200 sq ft × 0.25 = 50 cubic feet, about 1.85 cubic yards. The calculator above does the same sums for your own bed.
How deep should mulch be?
Shallower than many people think. University of Maryland Extension advises one to three inches depending on the material: bark or wood chips 1 to 3 inches, pine needles or leaves 2 to 3, compost about 1. It also warns that plants can decline and even die from too much mulch, and says to keep mulch about 3 inches clear of tree trunks.
How many bags of mulch are in a cubic yard?
A cubic yard is 27 cubic feet, so it takes 13.5 of the common 2 cu ft bags, or 9 of the 3 cu ft size. Check the volume printed on the bag you are buying, since sizes vary between products.
How much does a cubic yard of mulch cover?
It depends on how thick you spread it: about 324 square feet at 1 inch, 162 at 2 inches and 108 at 3 inches. The thinner the layer, the further a yard goes, which is why this calculator asks for depth as well as area.
Should I buy mulch in bags or bulk?
Bags are convenient for small beds and easy to carry. Bulk mulch by the cubic yard means less plastic and is often cheaper for larger areas, but it needs a truck or a delivery fee and a place to tip the pile. To decide, compare the bag price times the number of bags with the bulk price plus delivery.