Mulch Calculator
Work out how much mulch, bark or compost you need for a garden bed — and how many bags.
Mulch settles after spreading. For larger beds, bulk delivery by the cubic metre or cubic yard is usually cheaper than bags.
About this tool
Enter the size of your garden bed and how deep you want the mulch to get the volume in m³ or cubic yards, plus how many bags that is. Works for bark mulch, wood chips, compost and soil improver.
Frequently asked questions
5–8 cm (2–3 in) is ideal for most beds: deep enough to suppress weeds and hold moisture, but not so deep that it smothers roots. Keep mulch a few centimetres away from tree trunks and stems.
Multiply the bed's length × width × depth to get the volume, then divide by the bag size. A 4 × 2 m bed at 5 cm deep needs 400 litres — eight 50-litre bags.
One cubic yard covers about 108 ft² at 3 in deep, 162 ft² at 2 in, or 324 ft² at 1 in.
Usually yes once you need more than about 1 m³ (around 1.5 cubic yards). Bulk loads cost less per unit, but you need space for the delivery and a way to move it.
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