HowMuchIt

HowMuchIt / Mulch, soil, gravel

How much mulch, soil or gravel do I need?

Mulch, topsoil and gravel are all sold by volume, so the question is always the same: how big is the area and how deep do you want it? One cubic yard covers 324 square feet one inch deep; the rest is arithmetic.

A rusty wheelbarrow full of brown wood chip mulch beside a raised garden bed with a young shrub, a garden rake, a plain burlap sack and a pile of grey gravel on the lawn.
Mulch, soil, gravel: all sold by volume.

Work out your mulch, soil or gravel

The same rule, without the form: one cubic yard covers
DepthArea covered by 1 cubic yard
1 in324 sq ft
2 in162 sq ft
3 in108 sq ft
4 in81 sq ft
6 in54 sq ft

Cubic yards = area in sq ft x depth in inches / 324. A cubic yard is 27 cubic feet.

How deep for each job

Around trees, shrubs and flower beds, about three inches of coarse wood chips or shredded bark is the depth the extension services agree on. Keep the mulch pulled back from the trunk, so the base of the tree stays bare. A new lawn needs a deeper layer of good topsoil, four to six inches once it settles. A gravel path needs at least two inches on top, or weeds find their way through.

Bags or bulk

Bags are usually two or three cubic feet, so a cubic yard is nine to fourteen bags. Bags are easy to carry and store; bulk is delivered by the cubic yard and suits big areas. The label on the bag gives its real volume, and that is the number to type. For an odd-shaped bed, split it into rectangles, add up their areas, and type the total.

Before you spread

  • Weed the bed first: mulch on top of weeds does not stop them.
  • Rake soil and gravel level as you go, then measure the depth in a few spots.
  • Water a new lawn's topsoil lightly to settle it before seeding.

Good to know

  • About 3 inches of coarse wood chip or shredded bark mulch is enough around trees, shrubs and beds.1,2,3
  • Do not pile mulch against tree trunks. Pull it back so the trunk base stays bare.2,3,4
  • There are 27 cubic feet in one cubic yard.5,6,7
  • One cubic yard covers 324 square feet at 1 inch deep. So cubic yards = area (sq ft) x depth (inches) / 324.5,6
  • Bagged mulch is usually sold in 2- or 3-cubic-foot bags. Check the label for the actual volume.7,8
  • A new lawn needs 4 to 6 inches of good-quality topsoil.9,10
  • A gravel path needs a top gravel layer at least 2 inches thick.11,12

How we checked this page

Checked on October 26, 2026. We kept a fact only when two independent publishers agree, and each one is numbered to its sources below. Where sources give different numbers, we keep only what they share. We never write a price. This page was written with an AI assistant and checked against the sources below.

Sources

  1. Mulch Myths (HO-106), University of Kentucky Cooperative Extension Service
  2. Mulching Trees and Shrubs, The Morton Arboretum
  3. How deep should the mulch layer be around trees and shrubs?, Iowa State University Extension and Outreach
  4. How to mulch (Extension for Real Life blog), Mississippi State University Extension
  5. Calculate mulch, soil needs for plant beds (Southern Gardening, 1997), Mississippi State University Extension
  6. How Much Compost, Soil or Mulch Do I Need to Purchase?, Texas AgriLife Extension Service (Travis County)
  7. How Much Mulch Do I Need?, Bob Vila
  8. How Many Bags of Mulch Do I Need?, Angi
  9. Lawn Establishment, Penn State Extension
  10. Seeding a New Lawn [video], University of New Hampshire Cooperative Extension
  11. 5 Steps to a Successful Gravel Path, Fine Gardening (Taunton)
  12. Lay Your Own Path, Garden Design
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