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Mulch Calculator

This mulch calculator works out how much mulch, soil or compost you need for a garden bed, a tree ring, a raised bed or planters: enter the size in feet and the depth in inches, and you instantly see cubic feet, cubic yards and the number of bags to buy.

Example: Shape of the area: rectangle (bed, raised bed, box) · Length 10 ft · Width 4 ft · Depth 3 in · Number of identical areas 1 · Extra 10 % · Bag size: 2 cu ft → Mulch needed: 10 cu ft (0.37 cu yd · 283 L). Source: Iowa State University Extension and Outreach – Using Mulch in the Garden (2 to 4 inches, coarser mulches on the higher end; no more than 4" around woody plants). Updated: .

ft
ft
in
Mulch: 2–4 in; raised bed: fill height
e.g. 6 planters or 2 raised beds
%
for settling, uneven ground and leftovers
My ToolboxYour inputs are saved in this browser only.

Result

Mulch needed
10 cu ft (0.37 cu yd · 283 L)
Including extra
11 cu ft (0.41 cu yd · 311 L)
Bags
6 bags of 2 cu ft
Bags by size
BagBags
0.75 cu ft15
1 cu ft11
1.5 cu ft8
2 cu ft6
3 cu ft4
Working
Area 40 ft² × 3 in deep × 1 = 10 cu ft (0.37 cu yd · 283 L); + 10% extra = 11 cu ft (0.41 cu yd · 311 L).

How it is calculated

How much mulch do I need? The formula

One cubic yard is 27 cubic feet. Mulch and soil in bags are sold by the cubic foot, so the bag count is simple: 10 cu ft with 10% extra is 11 cu ft, or 6 bags of 2 cu ft.

How deep should mulch be?

Iowa State University Extension recommends 2 to 4 inches of mulch – coarse material such as wood chips toward the upper end, fine material toward the lower end. It advises no more than 4 inches around woody plants and feathering the mulch away from trunks rather than piling it up in a “mulch volcano”.

Filling a raised bed

For a raised bed, enter the inside length and width and the fill height. Many gardeners fill in layers – coarse material at the bottom, then compost, then potting or garden soil; calculate each layer with its own depth. A 8 × 4 ft raised bed filled 12 inches deep holds 32 cubic feet, about 1.2 cubic yards – bulk delivery often pays off at that size.

Extra and limits

Fresh soil settles after watering, the ground is uneven and bagged material is often looser than in the bed, so an extra percentage is preset and adjustable. The calculator works with volume only, not weight, because weight depends heavily on the material and its moisture. For concrete footings use the concrete calculator, for floor or yard area the square footage calculator, and for any other shape the volume calculator.

Frequently asked questions

How many bags of mulch do I need?

Multiply length × width in feet by the depth in inches ÷ 12 to get cubic feet, then divide by the bag size. A 10 × 4 ft bed at 3 inches needs 10 cu ft – five 2 cu ft bags, six with 10% extra.

How many square feet does a yard of mulch cover?

One cubic yard (27 cu ft) covers 162 square feet at 2 inches, 108 square feet at 3 inches and 81 square feet at 4 inches.

How many bags of mulch are in a yard?

A cubic yard is 27 cubic feet: 13.5 bags of 2 cu ft or 9 bags of 3 cu ft.

How much soil do I need for a raised bed?

Inside length × width × fill depth. An 8 × 4 ft bed filled 12 inches deep needs 32 cubic feet, about 1.2 cubic yards or 16 bags of 2 cu ft.

How deep should mulch be?

Two to four inches, according to Iowa State University Extension – coarser mulches deeper, finer ones shallower, and never piled against tree trunks.

Sources and legal basis

As of: · Editorial policy

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