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Mulch Calculator

Turn the size of a garden bed into cubic yards of bulk mulch or the number of bags to buy.

Quick answer

Cubic yards = length × width (ft) × depth (in) ÷ 12 ÷ 27. A 20 × 10 ft bed at 3 inches needs 1.85 cubic yards, or 25 two-cubic-foot bags. Laying a path too? Use the gravel calculator.

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  • Updated October 2026
ft
ft
in

Cubic yards needed

1.85 yd³

In cubic metres
1.42 m³
Cubic feet
50 ft³
2 cu ft bags
25
3 cu ft bags
17
50 litre bags
29
Show the working
  1. 20 × 10 × (3 ÷ 12) = 50 ft³
  2. 50 ÷ 27 = 1.85 yd³

About the Mulch calculator

Mulch is sold in bulk by the cubic yard or in bags, usually 2 or 3 cubic feet in the US. One cubic yard is 27 cubic feet, so it equals about 13.5 two-cubic-foot bags or 9 three-cubic-foot bags.

A 2–3 inch layer is the usual recommendation for beds: enough to suppress weeds and hold moisture without smothering roots. Keep mulch a few inches away from tree trunks and plant stems. Topping up an existing bed often needs only 1 inch.

How to use it

  1. Choose feet or metres.
  2. Enter the length and width of the bed (split odd shapes into rectangles and add them).
  3. Enter the depth — 3 inches for new beds, 1–2 inches to refresh.
  4. Read cubic yards for bulk delivery, or the number of bags.

The formula

Cubic yards = Length (ft) × Width (ft) × Depth (in) ÷ 12 ÷ 27

  • Bags = cubic feet ÷ bag size, rounded up.

Worked example

A 20 × 10 ft bed, 3 inches deep

  1. 20 × 10 × (3 ÷ 12) = 50 cubic feet.
  2. 50 ÷ 27 = 1.85 cubic yards.
  3. Or 25 two-cubic-foot bags.

Frequently asked questions

How much does a cubic yard of mulch cover?

About 108 sq ft at 3 inches deep, 162 sq ft at 2 inches, or 324 sq ft at 1 inch.

Is bulk mulch cheaper than bags?

For more than a couple of cubic yards, bulk delivery is usually cheaper per yard — but check the delivery fee and that you have somewhere to tip it.

How deep should mulch be?

2–3 inches for most beds. Deeper than about 4 inches can keep soil too wet and starve roots of air.

Results are estimates for planning — check critical figures with a professional or the official source.

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