Mulch calculator

How to use

1. Pick the units and the bed shape: rectangle, circle, or an area you already know.
2. Enter the size and the depth of mulch you want.
3. Set the bag size printed on the bags you buy and read off the volume and the bag count.

How it works

• area: length × width for a rectangle, π × diameter² ÷ 4 for a circle;
• volume = area × depth (depth converted to feet or metres);
• cubic yards = cubic feet ÷ 27; litres = cubic metres × 1,000;
• bags = volume ÷ bag size, rounded up.

Example

A bed 15 ft long and 6 ft wide, mulched 3 inches deep with 2 cu ft bags:

• area 15 × 6 = 90 ft²; 3 in = 0.25 ft;
• volume 90 × 0.25 = 22.5 ft³, or 22.5 ÷ 27 = 0.83 yd³;
• 22.5 ÷ 2 = 11.25, so buy 12 bags.

In metric: a 5 × 2 m bed with a 7 cm layer needs 10 × 0.07 = 0.7 m³ (700 L), which is 14 bags of 50 L.

Tips and common mistakes

• Measure depth in inches or centimetres, not feet or metres: the fields expect the small unit.
• Bulk mulch is sold by the cubic yard or cubic metre and is usually cheaper than bags for big areas.
• Refreshing an old layer needs less: enter only the depth you are adding.