How much mulch do I need for 100 square feet?

At a 3 inch depth, 100 sq ft needs about 25 cubic feet of mulch, which is 0.93 cubic yards or roughly 13 bags of 2 cubic feet each. Adjust the depth and bag size for your product.

How deep should mulch be?

Two to three inches is a common depth around trees and shrubs. Deeper layers can hold too much moisture against stems, and very thin layers do not suppress weeds well.

How many bags of mulch are in a cubic yard?

A cubic yard is 27 cubic feet. Bags of 2 cubic feet mean about 13.5 bags per yard, so plan on 14 bags. Bags of 3 cubic feet mean about 9 bags per yard.

Should I add waste to a mulch order?

Mulch is usually forgiving, so a waste allowance is optional. For irregular beds it can help to round up slightly, and leftover mulch can top up thin spots later.

Mulch Calculator

Enter the size of your garden bed and the depth of mulch you want to estimate the volume in cubic feet and cubic yards, plus the number of bags to buy.

Mulch needed

1.85 cubic yards

Or about 25 bags at 2 cu ft each.

Bed area: 200 sq ft
Volume: 50 cu ft
Bags to buy: 25 bags

Planning note

Bulk mulch is usually sold by the cubic yard and is often cheaper than bags for large beds. Keep mulch a few inches away from plant stems and siding.

How this calculator works

The calculator finds the bed area, multiplies it by the depth converted to feet, adds an optional waste allowance, and converts the result to cubic yards and bags.

area        = length × width
volume      = area × (depth in ÷ 12)          cubic feet
cubic yards = volume with waste ÷ 27
bags        = round up (volume with waste ÷ bag size)

Assumptions

The bed is rectangular. Split irregular beds into rectangles and add the results.
Mulch depth and bag size are the values you enter; bag sizes vary by brand.
Bag counts are rounded up because mulch is sold in whole bags.

Worked example

A 20 ft by 10 ft bed is 200 sq ft. At 3 inches deep, the volume is 200 × 0.25 = 50 cubic feet, which is 50 ÷ 27 = 1.85 cubic yards, or 25 bags of 2 cubic feet each.

Frequently asked questions

How much mulch do I need for 100 square feet?: At a 3 inch depth, 100 sq ft needs about 25 cubic feet of mulch, which is 0.93 cubic yards or roughly 13 bags of 2 cubic feet each. Adjust the depth and bag size for your product.
How deep should mulch be?: Two to three inches is a common depth around trees and shrubs. Deeper layers can hold too much moisture against stems, and very thin layers do not suppress weeds well.
How many bags of mulch are in a cubic yard?: A cubic yard is 27 cubic feet. Bags of 2 cubic feet mean about 13.5 bags per yard, so plan on 14 bags. Bags of 3 cubic feet mean about 9 bags per yard.
Should I add waste to a mulch order?: Mulch is usually forgiving, so a waste allowance is optional. For irregular beds it can help to round up slightly, and leftover mulch can top up thin spots later.

Related calculators

Last updated: September 25, 2026