Home & Yard

Mulch calculator

Find out how many cubic yards or bags of mulch you need for your beds, and whether bulk or bagged mulch is cheaper.

Your numbers

ft
ft
in
2–3 in is ideal for most beds.
$
$

Results

Estimates only. Measure carefully and confirm quantities and material weights with your supplier before ordering.

How much mulch do you need?

Mulch is sold in bags measured in cubic feet, or in bulk by the cubic yard. Either way, the amount you need is simply the area of your beds multiplied by how deep you want the mulch. This calculator does the unit conversions for you and rounds bags up to whole bags.

How the calculator works

  1. It works out the area of the bed in square feet. For a ring around a tree, choose circle and enter the diameter of the ring.
  2. It multiplies the area by the depth in feet (inches ÷ 12) to get cubic feet.
  3. It divides by 27 to get cubic yards, and by the bag size to get the number of bags.

The formula

Cubic feet = area (sq ft) × depth (in) ÷ 12 Cubic yards = cubic feet ÷ 27 Bags = cubic feet ÷ bag size, rounded up

A handy rule: one cubic yard covers 324 square feet at 1 inch deep, 162 square feet at 2 inches and 108 square feet at 3 inches. One cubic yard equals 13.5 bags of 2 cubic feet.

Worked example

A border along a fence is 30 ft long and 4 ft wide, and you want 3 inches of mulch.

Area: 30 × 4 = 120 sq ft. Volume: 120 × 3 ÷ 12 = 30 cubic feet, or about 1.11 cubic yards. In 2 cu ft bags, that is 15 bags.

If bags cost $4 each, that is $60. If bulk mulch is $40 a yard, the mulch itself is about $44, though delivery fees can change the picture for small orders.

How deep should mulch be?

  • 2–3 inches is the sweet spot for most flower and shrub beds. It holds moisture and blocks light to weed seeds without smothering roots.
  • Topping up an existing bed usually needs only 1 inch, since old mulch breaks down slowly.
  • Fine mulch such as shredded leaves can go a little thinner; coarse wood chips can go a little deeper.
  • Keep it off trunks. Leave a few inches of space around tree trunks and plant stems. "Mulch volcanoes" piled against bark trap moisture and invite rot and pests.

Bagged or bulk?

Bags are convenient for small jobs and easy to carry into a back garden. Bulk mulch is usually much cheaper per yard once you need more than one or two cubic yards, but many suppliers charge for delivery. Enter both prices above to see which comes out ahead for your order.

Frequently asked questions

How many bags of mulch are in a yard?

A cubic yard is 27 cubic feet, so it equals 13.5 bags of 2 cubic feet, 18 bags of 1.5 cubic feet or 9 bags of 3 cubic feet.

How much area does a bag of mulch cover?

A 2 cubic foot bag covers about 12 square feet at 2 inches deep, or 8 square feet at 3 inches deep.

How often should I replace mulch?

Most organic mulches need topping up about once a year, often in spring. You usually only need to add an inch or so rather than replacing all of it.

Does this work for rubber mulch or stone?

Yes for volume. Rubber mulch is often laid at a similar depth, and decorative stone is usually sold by weight, so for stone use the gravel calculator to get tons.

How much mulch do I need around a tree?

Choose the circle shape and enter the diameter of the mulch ring, for example 6 feet. At 3 inches deep, a 6 foot ring needs about 7 cubic feet, or 4 bags of 2 cubic feet.

Last reviewed November 2026. Spotted an error? Tell us.