Mulch Calculator
Updated 2026-10-14
Enter the size of your garden bed and how deep you want the mulch. The calculator tells you how much to order in bulk and how many bags that would be.
How the mulch calculator works
Mulch is sold by volume: in bags measured in cubic feet or liters, or in bulk by the cubic yard or cubic meter. To find the volume you need, multiply the area of the bed by the depth of mulch. Depth is entered in inches or centimeters, so it's converted first. The number of bags is the total volume divided by the size of one bag, rounded up.
Cubic yards = cubic feet ÷ 27
Bags = cubic feet ÷ bag size, rounded up
Worked example
A flower bed 20 ft long and 5 ft wide has an area of 100 sq ft. At 3 inches deep (0.25 ft), it needs 25 cubic feet of mulch, which is 0.93 cubic yards. Mulch in 2 cubic foot bags would take 12.5 bags, so buy 13.
How deep should mulch be?
| Situation | Recommended depth |
|---|---|
| Top-up of existing mulch | 1 in (2–3 cm) |
| Fine mulch (shredded bark, compost) | 2 in (5 cm) |
| Standard flower and shrub beds | 2–3 in (5–8 cm) |
| Coarse bark chips, paths, weed control | 3–4 in (8–10 cm) |
Deeper isn't always better. More than about 4 inches can stop water and air reaching the soil. Keep mulch a few inches away from tree trunks and plant stems: mulch piled against bark ("volcano mulching") holds moisture against the trunk and invites rot and pests.
Bags or bulk?
Bags are clean and easy for small beds or for topping up. For larger areas, bulk mulch from a landscape supplier is usually much cheaper per cubic yard. One cubic yard equals 27 cubic feet, so it replaces 13.5 bags of 2 cubic feet. As a rough guide, once you need more than about one cubic yard, compare the bulk price including delivery against the bag price. Bulk loads need somewhere to be tipped and a wheelbarrow to move them, so factor in the work too.
Measuring awkward beds
- Curved or irregular beds: measure the longest length and the average width, or split the bed into a few rough rectangles and add them up.
- Round beds: the area is 3.14 × radius × radius. A round bed 6 ft across has a radius of 3 ft and an area of about 28 sq ft. Enter that as 28 × 1 in the calculator.
- Beds around trees: measure the ring as a square and subtract a little for the trunk. A small overestimate is fine.
- Several beds: add the areas together and enter the total as length × 1, or run the calculator for each bed.
Which mulch to choose
Organic mulches such as shredded bark, wood chips, pine needles and compost slowly break down and feed the soil, so they need topping up every year or two. Inorganic mulches such as gravel or rubber last longer but don't improve the soil. Dyed mulch is fine for most ornamental beds, but many gardeners prefer undyed material around vegetables and herbs.
Frequently asked questions
- How many bags of mulch are in a cubic yard?
- A cubic yard is 27 cubic feet, so it equals 13.5 bags of 2 cubic feet, or 9 bags of 3 cubic feet.
- How much area does a cubic yard of mulch cover?
- At 2 inches deep, one cubic yard covers about 162 sq ft. At 3 inches it covers 108 sq ft, and at 4 inches it covers 81 sq ft.
- How much does a 2 cubic foot bag cover?
- At 2 inches deep it covers 12 sq ft, and at 3 inches deep it covers 8 sq ft.