Mulch calculator

Q: How many bags of mulch are in a cubic yard?

**13.5** if the bags are the standard 2 cubic feet, which is what most big-box stores stock. Nine if you have 3 cu ft bark nuggets, and 18 for 1.5 cu ft bags. Since you cannot buy half a bag, order 14 of the 2 cu ft bags.

Q: How much area does a yard of mulch cover?

It depends entirely on depth: **324 ÷ depth in inches**. That is 162 sq ft at 2 in, 108 sq ft at 3 in and 81 sq ft at 4 in. The familiar "100 square feet" figure is the 3 in case rounded down.

Q: Can I put new mulch on top of old mulch?

Yes, but measure the existing layer first and top up to a **total** of 2–3 inches rather than adding a fresh 3 inches every spring. If the old mulch has matted, rake it to break the crust before adding more. Beds that get a full layer annually are usually the ones that end up smothering their own plants.

Enter the bed area and how deep you want the mulch. Depth is what decides everything here: one cubic yard covers 162 sq ft at 2 in but only 81 sq ft at 4 in, so any coverage figure quoted without a depth is meaningless.

Mulch needed 0.97 cu yd

Same volume in cubic feet 26.3 cu ft

Bags of mulch 14 bags Rounded up.

One cubic yard covers, at this depth 108 sq ft 324 ÷ depth in inches.

Approximate weight, dry 535 lb Shredded bark runs 400–700 lb/cu yd dry and over 800 lb wet, so treat this as ±30%.

How the number is worked out

Volume is bed area × depth, with the depth converted from inches to feet. A 100 sq ft bed at 3 in is 100 × 0.25 = 25 cubic feet, or 0.93 cubic yards.

The figure worth remembering is the other way round. A cubic yard is 27 cubic feet, so spread at a depth of d inches it covers 324 ÷ d square feet:

2 in → 162 sq ft
3 in → 108 sq ft
4 in → 81 sq ft

Why "one yard covers 100 square feet" is not an answer

That rule of thumb is everywhere, and it is a rounded-down version of the 3 in figure. It happens to be about 7% conservative at 3 in, which is harmless. The problem is that it gets quoted with no depth attached, and people apply it at 4 in — where a yard reaches only 81 sq ft. On a 400 sq ft bed that is the difference between four yards and five.

Any mulch coverage number without a depth beside it is incomplete. That is the single most common error on competing calculators.

How deep to go

Penn State Extension and Ohio State University Extension both put the working range at 2–3 inches: enough to hold moisture and block light, shallow enough to let water and air through to the roots. More than 4 inches encourages adventitious roots that grow out of the trunk instead of the root system, and over time those can girdle the tree.

Around a tree, keep mulch off the bark entirely and leave the root flare visible. The common shorthand is 3-3-3 — at least 3 in back from the trunk, no more than 3 in deep, out to a 3 ft diameter.

If you are topping up existing mulch, measure what is already there first. Most beds only need an inch to look new, and mulch piled year on year is how beds end up 6 in deep.

Bags or bulk

The standard US retail bag holds 2 cubic feet, so a cubic yard is 13.5 bags. Bark nuggets often come in 3 cu ft bags (9 per yard) and some premium cedar in 1.5 cu ft (18 per yard) — the number on the bag is the only thing that settles it.

Bulk becomes the obvious choice somewhere around 3 cubic yards, which is 40-odd bags. Shredded bark is 400–700 lb per cubic yard dry, and over 800 lb after rain, so a half-ton pickup takes about one yard at a time, not two.

What this does not include

Settling and decomposition. Organic mulch loses roughly an inch a season.
Edging. Without a hard edge, mulch migrates onto the lawn and out of the bed.

Common cases

Questions people ask

How many bags of mulch are in a cubic yard?

13.5 if the bags are the standard 2 cubic feet, which is what most big-box stores stock. Nine if you have 3 cu ft bark nuggets, and 18 for 1.5 cu ft bags. Since you cannot buy half a bag, order 14 of the 2 cu ft bags.

How deep should mulch be?

Two to three inches. Penn State Extension and Ohio State University Extension both give that range — it holds moisture and blocks weed light while still letting air reach the roots. Going deeper does not suppress more weeds; past about 4 inches it starts to harm the plant.

How much area does a yard of mulch cover?

It depends entirely on depth: 324 ÷ depth in inches. That is 162 sq ft at 2 in, 108 sq ft at 3 in and 81 sq ft at 4 in. The familiar "100 square feet" figure is the 3 in case rounded down.

Can I put new mulch on top of old mulch?

Yes, but measure the existing layer first and top up to a total of 2–3 inches rather than adding a fresh 3 inches every spring. If the old mulch has matted, rake it to break the crust before adding more. Beds that get a full layer annually are usually the ones that end up smothering their own plants.

How much does a cubic yard of mulch weigh?

Shredded bark is roughly 400–700 lb per cubic yard dry, rising past 800 lb once it is wet. That matters for pickup loads: one yard is a sensible load for a half-ton truck, and two yards of wet mulch is not.

Last reviewed 2026-07-30