Mulch Calculator

Find out how many bags or cubic yards of mulch you need for your garden beds. Enter the bed size and depth, then compare bagged and bulk prices.

Bed shape
Bags needed
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Cubic yards–
Cubic feet–
Cost in bags–
Cost in bulk–

How much mulch do I need?

Mulch is sold by volume, in bags measured in cubic feet or in bulk by the cubic yard. To know how much to buy, multiply the area of your bed by the depth of mulch you want:

Cubic feet = length ft × width ft × (depth in ÷ 12)
Bags = cubic feet ÷ bag size · Cubic yards = cubic feet ÷ 27

Worked example

A flower bed is 10 feet by 12 feet, and you want 3 inches of mulch.

  • Volume: 10 × 12 × (3 ÷ 12) = 30 cubic feet
  • In 2 cubic foot bags: 30 ÷ 2 = 15 bags
  • In bulk: 30 ÷ 27 = 1.11 cubic yards

Bag coverage at common depths

Depth2 cu ft bag covers1 cubic yard covers
1 inch24 sq ft324 sq ft
2 inches12 sq ft162 sq ft
3 inches8 sq ft108 sq ft
4 inches6 sq ft81 sq ft

Bags or bulk?

For a few small beds, bags are convenient: you can carry them anywhere and buy only what you need. For large areas, bulk mulch is usually cheaper per cubic foot, but you may pay a delivery fee and need somewhere to put the pile. Enter both prices above and the calculator shows which costs less for your job.

Mulching tips

  • Pull weeds and water the soil before spreading mulch.
  • Keep mulch a few inches away from tree trunks and plant stems to prevent rot. Avoid piling it up around trees in a "volcano" shape.
  • Top up as needed, since organic mulch breaks down over time and improves the soil as it does.
  • For deeper fills like raised beds, the cubic yard calculator handles any depth and shape.

Last reviewed October 2026.

Frequently asked questions

How many bags of mulch are in a cubic yard?

One cubic yard is 27 cubic feet, so it equals 13.5 bags of 2 cubic feet, or 9 bags of 3 cubic feet. Most bagged mulch in the US comes in 2 cubic foot bags.

How deep should mulch be?

A layer of about 2 to 3 inches is a common recommendation for garden beds. It is deep enough to hold in moisture and block weeds, but not so deep that it smothers roots. Keep mulch a few inches away from tree trunks and plant stems.

How much area does a bag of mulch cover?

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

Is bulk mulch cheaper than bags?

For larger jobs, bulk mulch delivered by the cubic yard is often cheaper per cubic foot than bags. Bags are easier for small beds, top-ups and places a delivery truck cannot reach. Enter both prices to compare.

How do I measure a curved or round garden bed?

For a round bed, measure across the middle and choose the circle shape. For an irregular bed, break it into rough rectangles and circles, work out each part, and add them together.

Do I need to remove old mulch first?

Not usually. If the old layer is thin and broken down, you can add a fresh layer on top. If it is already deep or matted, loosen it with a rake and add less new mulch so the total depth stays around 2 to 3 inches.