Mulch calculator

How to use the mulch calculator

Estimate how much mulch you need for a garden bed. Enter the bed dimensions or a known area, then choose the depth, bag size, and waste allowance.

1. Choose Feet / inches or Metres / cm.
2. Enter the bed Length and Width, or enter Or a known area to override the dimensions.
3. Enter the Depth for the mulch layer.
4. Choose the Bag size and Waste %.
5. Review the calculated volume and rounded-up bag count.

What to enter

Feet / inches or Metres / cm

Choose the unit system. The default is Feet / inches.

Length

Bed length. The default is 20 ft in imperial mode or 20 m in metric mode.

plus inches

Add inches to Length in imperial mode, or centimetres in metric mode. The default is 0.

Width

Bed width. The default is 10 ft in imperial mode or 10 m in metric mode.

plus inches

Add inches to Width in imperial mode, or centimetres in metric mode. The default is 0.

Or a known area

Optional area input in sq ft or m². When filled, it overrides Length × Width.

Depth

Mulch depth in inches or centimetres. The default is 3 in, with a field hint of 2–3 in for beds and 3–4 in for weed suppression.

Bag size

Bag volume in cubic feet. Choose 0.75, 1, 1.5, 2, or 3 cu ft. The default is 2 cu ft.

Waste %

Extra material for settling and other loss. The default is 5%. Enter a value from 0% to 50%.

Example: 200 sq ft bed at 3 inches deep

Using the default imperial settings, enter Length 20 ft, Width 10 ft, Depth 3 in, Bag size 2 cu ft, and Waste % 5. Area: 20 × 10 = 200 sq ft. Net volume: 200 × 3 ÷ 12 = 50 cu ft. Volume with waste: 50 × 1.05 = 52.5 cu ft. Cubic yards: 52.5 ÷ 27 = 1.9444..., which the tool displays as 1.94 cu yd. Exact bags: 52.5 ÷ 2 = 26.25 bags. Because bags are rounded up, the result is 27 bags.

How the mulch calculation works

The tool calculates area as Length × Width unless Or a known area is provided. It converts metric inputs to the calculator's internal feet and inches. Net volume is area × depth ÷ 12 in cubic feet. The waste factor is 1 + Waste % ÷ 100, so the default 5% becomes 1.05. The adjusted volume is then converted using 27 cu ft = 1 cu yd. Exact bags equal adjusted cubic feet ÷ selected bag size, and the bag count is rounded up to a whole bag. Displayed volume and breakdown values are rounded to two decimals.

Reading the results

The main result shows Mulch to order in cu yd for imperial mode or m³ for metric mode. It also shows the number of bags, rounded up to a whole bag, and the area to cover. The breakdown includes net volume, volume with waste, cubic yards, cubic metres, and exact bags. Mulch is calculated by volume only; this tool does not estimate weight.

Limitations and common mistakes

• The calculator assumes one uniform mulch depth across the selected area.
• Or a known area overrides Length × Width, so do not enter a smaller area accidentally.
• Bag counts are rounded up, but the result does not account for a retailer's actual fill level or bag variation.
• Waste is limited to 0%–50% and is an allowance selected by you, not a guarantee of coverage.

Frequently asked questions