Garden and landscaping tool

Mulch Calculator

Find out how much mulch you need for garden beds, borders and landscaped areas. Enter your dimensions and desired depth to estimate total volume, bag quantities and the amount to order with an optional extra-material allowance.

Enter garden-bed measurements

Choose your bed shape, set the units and enter the desired mulch depth.

Garden-bed shape

Length measurement unit

Rectangular bed

Length

Width

Mulch depth and materials

Desired mulch depth

Depth unit

Bag volume

Bag volume unit

Extra-material allowance (%) Use an allowance for settling, uneven surfaces or small losses. The appropriate amount depends on your project.

Reset

How to measure a garden bed

Measure the length and width of a rectangular bed.
For a circular bed, measure from the center to the outside edge.
For multiple beds, calculate each area separately or use the multiple-bed option.
Choose a mulch depth appropriate for the material and plants.
Check the volume printed on your mulch bags before buying.

Useful volume conversions

1 m³ = 1,000 liters
1 m³ ≈ 35.3147 ft³
1 m³ ≈ 1.308 yd³
1 yd³ = 27 ft³
1 ft³ ≈ 28.3168 liters

How the mulch calculator works

First, the calculator finds the garden-bed surface area. It converts the selected depth to meters and multiplies area by depth to determine the volume. An optional extra-material allowance is then added, and the total is divided by the volume of one bag. The bag count is rounded up because mulch is generally purchased in whole bags.

Calculation formulas

Rectangular area = length × width Circular area = π × radius² Mulch volume = area × depth Volume with allowance = base volume × (1 + allowance percentage ÷ 100) Number of bags = round up (volume with allowance ÷ volume per bag)

Example: a rectangular garden bed

A bed measuring 5 m by 3 m has an area of 15 m². At a mulch depth of 7.5 cm (0.075 m), the base volume is 15 × 0.075 = 1.125 m³. Adding a 10% allowance gives 1.2375 m³. With 50-liter bags, the estimate is 1,237.5 ÷ 50 = 24.75, which rounds up to **25 bags**.

Choosing the depth

The appropriate depth depends on the type of mulch, the plants, the existing surface and the purpose of the mulch. Follow the guidance for your specific material and avoid piling mulch against tree trunks or plant stems. If you are topping up an existing bed, measure the additional depth you intend to add rather than the total depth already present.

Bagged mulch or bulk delivery?

Bagged mulch can be convenient for small beds and precise placement. Bulk mulch may be more economical for larger areas, but suppliers can use different definitions and loading tolerances. Confirm whether a bulk quote is sold by cubic yard, cubic meter, weight or another unit before ordering.

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