Mulch Calculator (Cubic Yards and Bags)

Enter the bed size or area and the depth you want, and this mulch calculator gives cubic yards, cubic metres and bags of 2 or 3 cu ft, plus the cost by the bag or in bulk. Three inches is the usual depth for beds; two for a top-up.

Mulch calculator

How it works

Volume = area × depth (inches ÷ 12), times the number of beds
Cubic yards = cubic feet ÷ 27 (a cubic yard covers 108 sq ft at 3 in, 162 sq ft at 2 in)
Bags = cubic feet ÷ bag size, rounded up (13.5 two-cubic-foot bags per yard)
Weight about 20 lb per cubic foot for damp bark mulch; bark and wood waste is listed at about 15 lb per cu ft dry (Engineering ToolBox)

Worked example

A 20 × 8 ft bed mulched 3 in deep:

Units: Feet and inches
Measure by: Length and width
Length: 20 ft
Width: 8 ft
Beds this size: 1
Depth: 3 in
Bag size: 2 cu ft bag
Price per bag (optional): $0
Price per cubic yard, bulk (optional): $0

The calculator gives:

Mulch needed: 1.48 cu yd (1.13 m³)
Bags: 20 × 2 cu ft bags
Volume: 40 cu ft over 160 sq ft at 3 in
Approximate weight: 800 lb (363 kg) at about 20 lb per cu ft for damp bark mulch; dry shredded mulch is lighter

Forty cubic feet is 1.48 cubic yards, or 20 bags of 2 cu ft. That is about 800 lb of damp mulch: a load for a pickup rather than a car. Bulk mulch delivered by the yard is usually cheaper once you pass about 15 bags.

Material and waste notes

Keep mulch 2 to 3 in away from tree trunks and plant stems and no deeper than 4 in; volcano mulching rots bark.
Measure beds as rectangles and add them, or use the square footage calculator for curves.
Bags settle and vary; bulk mulch is measured loose in the truck and settles too. The extra is small either way.
Rubber mulch and stone are much heavier per cubic foot; use the gravel calculator for stone.

Frequently asked questions

How many bags of mulch in a yard?

13.5 bags of 2 cu ft, or 9 bags of 3 cu ft.

How much does a yard of mulch cover?

About 108 sq ft at 3 in deep, 162 sq ft at 2 in, and 81 sq ft at 4 in.

How deep should mulch be?

2 to 3 in for beds, 3 to 4 in for paths and for suppressing weeds on bare soil. Top up by an inch a year.

How much does a yard of mulch weigh?

Roughly 400 to 800 lb depending on the type and how wet it is; bark and wood mulch is listed around 15 lb per cu ft dry.

Is bulk mulch cheaper than bags?

Usually, once you need more than about a yard (15 bags). Delivery fees decide it for small jobs.

Sources

Engineering ToolBox, "Densities of Common Materials" (bark and wood mulch, soils)

Last reviewed: 26 September 2026. The calculation is covered by automated tests with known answers taken from the sources above. Found an error? Please let us know.