Mulch Calculator

By BRIX Editorial Team · Updated October 12, 2026

To figure mulch, multiply the bed's square footage by the depth in inches, then divide by 324 to get cubic yards; one cubic yard covers 324 sq ft at 1 inch deep. A 60 × 5 ft bed at 3 inches takes 2.78 cubic yards, or 38 bags of 2 cubic feet.

Bulk mulch2.78 cu yd

Area: 300 sq ft
Volume: 75 cu ft
Bags (2 cu ft each): 38
One yard covers, at this depth: 108 sq ft

300 sq ft at 3 in deep takes 2.78 yards, or 38 bags. At a few yards or more, compare a bulk delivery price against the bag count.

Key takeaways

Cubic yards = square feet × depth (in) ÷ 324.
One cubic yard covers 324 sq ft at 1 in, 162 sq ft at 2 in and 108 sq ft at 3 in.
Clemson Extension says fine wood and bark mulch should be no more than 2–3 in deep; coarse bark nuggets can go to 4 in.
A cubic yard is 27 cu ft, so it equals 13.5 bags of 2 cu ft.
Keep mulch pulled back from tree trunks and plant stems.

How do you calculate how much mulch you need?

Measure the bed's area in square feet, multiply by the depth in feet to get cubic feet, and divide by 27 for cubic yards. The shortcut is square feet × inches ÷ 324, because a cubic yard spread 1 inch thick covers 324 square feet. For bags, divide cubic feet by the bag size.

Formula

Cubic yards = Area (sq ft) × Depth (in) ÷ 324

Area: length × width, or π × r² for a round bed
Depth: finished mulch depth in inches
324: sq ft one cubic yard covers at 1 in (27 cu ft × 12)

1
Measure each bed.
Length × width for rectangles. For an irregular bed, break it into rectangles or pace off an average length and width.
2
Pick a depth.
Use 2–3 in for fine shredded mulch and up to 3–4 in for coarse bark. Subtract any old mulch still in place.
3
Convert to yards.
Multiply square feet by inches and divide by 324.
4
Convert to bags if needed.
Multiply yards by 27 for cubic feet, then divide by the bag size (usually 2 cu ft).

Tree rings use the circle formula. 8 rings 6 ft across are 8 × π × 3² = 226 sq ft. At 3 in, that's 2.09 yards or 29 bags.

How many square feet does a yard of mulch cover?

Mulch coverage by depth (for a 1,000 sq ft area in the last two columns)
Depth	One cubic yard covers (sq ft)	Cubic yards for 1,000 sq ft	2 cu ft bags for 1,000 sq ft
1 in	324	3.09	42
2 in	162	6.17	84
3 in	108	9.26	125
4 in	81	12.35	167

Coverage per yard from Clemson Extension's 324 sq ft at 1 in; the rest is computed with the calculator above.

How deep should mulch be?

Two to three inches is right for most beds. Clemson Extension says fine wood and bark mulch should not be more than 2–3 in deep, coarse pine bark nuggets can be up to 4 in, and grass clippings or shredded leaves no more than 2 in. The Morton Arboretum recommends 3–4 in of medium to coarse mulch under trees and shrubs, and only a couple of inches in perennial beds.

Mulch depth by job
Job	Depth	Note
Annual top-up over existing mulch	1–2 in	Measure what's left before you order
New bed, fine shredded mulch	2–3 in	Clemson's maximum for fine wood and bark mulch
Trees and shrubs, coarse bark	3–4 in	Keep it a few inches off the trunk
Perennial beds	about 2 in	Morton Arboretum: a couple of inches
Leaves or grass clippings	2 in max	Thicker mats shed water

Bulk mulch or bags?

A cubic yard of bulk mulch equals 13.5 bags of 2 cu ft. For small beds, touch-ups and places a truck can't reach, bags are simpler. For a few yards or more, price bulk delivery against the bags and the time to haul and open them; and check the supplier's delivery minimum and fee.

Common mulch estimating mistakes

Ordering the full depth over old mulch. Measure what's there. A 1 in top-up needs a third of a 3 in install.
Mulch volcanoes. Piling mulch against trunks invites rot and pests. Plan a donut, not a cone.
Forgetting curved beds. Kidney-shaped beds are easy to underestimate. Break them into rectangles and circles.
Mixing bag sizes. Bags come in 1.5, 2 and 3 cu ft. Use the size on the bag you're buying.
Skipping weeding and edging labor. Spreading is the easy part. Price bed prep on its own line.

Frequently asked questions

How much area does a yard of mulch cover?

One cubic yard covers about 324 sq ft at 1 in deep, 162 sq ft at 2 in, 108 sq ft at 3 in and 81 sq ft at 4 in. Divide 324 by your depth in inches.

How many bags of mulch are in a yard?

A cubic yard is 27 cu ft, so it equals 13.5 bags of 2 cu ft, 18 bags of 1.5 cu ft or 9 bags of 3 cu ft. Check the size printed on the bag.

How much mulch do I need for 1,000 square feet?

At 3 in deep, 1,000 sq ft takes 9.26 cubic yards, or 125 bags of 2 cu ft. At 2 in it's about 6.2 yards.

How deep should mulch be?

Two to three inches for most beds. Clemson Extension caps fine wood and bark mulch at 2–3 in and allows coarse bark nuggets up to 4 in; the Morton Arboretum recommends 3–4 in of coarse mulch under trees and shrubs.

How do I calculate mulch for a tree ring?

Use π × radius² for the area. A 6 ft ring has a 3 ft radius, so it's 3.14 × 9 = 28.3 sq ft. At 3 in, that's 28.3 × 3 ÷ 324 = 0.26 yards, or about 4 bags of 2 cu ft.

Should I remove old mulch before adding new?

Not usually. Rake out matted layers and measure what's left, then add enough to reach the target depth. Piling new mulch on a thick old layer can smother roots.

Sources

Clemson Cooperative Extension HGIC 1604 — Mulch (depth, 324 sq ft per yard at 1 in) (checked October 12, 2026)
The Morton Arboretum — How to Mulch Trees and Shrubs (checked October 12, 2026)

Mulch Calculator