How Much Mulch Do I Need?

At the usual 3 inch depth, one cubic yard of mulch covers 108 square feet, and one 2 cubic foot bag covers 8 square feet. So a 100 sq ft bed needs 0.93 cubic yards, or 13 bags. At 2 inches, a yard covers 162 sq ft; at 4 inches, 81 sq ft.

The quick formula: square feet × depth in inches ÷ 12 = cubic feet. Divide by 27 for cubic yards, or by 2 for 2 cu ft bags. The Mulch Calculator does this for rectangular, round and triangular beds, and the tables below use the same 2 cu ft bag so the numbers match.

How Far Does Mulch Go?

A shortcut for any depth: divide 324 by the depth in inches to get square feet per cubic yard.

Mulch Needed by Area

Cubic yards and 2 cu ft bags, before any extra. Bags are rounded up, as in the calculator.

Add about 10% to these figures. Fresh mulch settles, and some always spreads past the bed edges. With 10% added, a 100 sq ft bed at 3 inches needs 14 bags instead of 13, and a 200 sq ft bed needs 28 instead of 25.

How Deep Should Mulch Be?

Measure the depth of what is already in the bed before you buy. If 1.5 inches of old mulch remains and you want 3 inches, you only need to add 1.5, which halves the order.

Measuring Your Beds

The calculator has rectangle, circle and triangle shapes, and accepts feet, yards or meters. Measure after you edge the beds and pull weeds, so you are covering the real planted area.

Worked Example

A front yard has a 20 x 4 ft bed along the house, two 6 ft tree rings and a 10 x 10 ft corner bed, all to be covered 3 inches deep.

Bags or Bulk?

One cubic yard equals 13.5 bags of 2 cu ft, or 9 bags of 3 cu ft. To compare prices, multiply the bag price by 13.5 (for 2 cu ft bags) and compare it with the bulk price per yard plus delivery. Once a job needs more than a couple of cubic yards, bulk is often cheaper per yard and saves a lot of trips, but prices and delivery fees vary by region, so check both.

Bags make sense for small beds, for touch-ups, when you have no space for a pile, or when you want to spread the work over several weekends. Bulk makes sense for large areas, new beds and whole-yard refreshes. Ask where the truck can tip the load, and put a tarp down if it lands on a driveway or lawn.

Mulch and Plant Health

Other Materials for the Same Project

If you are edging a bed with stone, building a path or setting a patio next to your planting, the same area and depth method applies. See how much gravel you need for a path or base, and the paver patio materials list if the bed borders a new patio. The Gravel Calculator handles decorative stone in place of mulch.

The Short Answer

At 3 inches deep, plan on 1 cubic yard per 108 sq ft, or one 2 cu ft bag per 8 sq ft, then add 10%. Enter your bed shapes and depth in the Mulch Calculator to get cubic yards and bags in one step.