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Mulch Calculator
Mulch for garden beds — area, depth and bag size in, volume and bags out.
Bags needed
How it works
Volume (litres) = area (m²) × depth (cm) × 10 Bags = ceil(volume ÷ bag size) Example: 10 × 7.5 × 10 = 750 litres → 13 bags
Worked example: a 10 m² bed mulched 7.5 cm deep needs 10 × 7.5 × 10 = 750 litres, which is 0.75 m³, or ceil(750 ÷ 60) = 13 bags of 60 litres.
Frequently asked questions
How deep should mulch be?
Between 5 and 10 cm is typical. Less than 5 cm does little against weeds; much more than 10 cm can starve the soil of air.
Should mulch touch plant stems?
No. Keep it about 5 cm clear of stems and trunks, or damp mulch held against bark can cause rot.
How often do I top it up?
Mulch breaks down over a year or so. Check each spring and top up to the target depth rather than piling it ever higher.
Bark or wood chip?
Both work. Bark lasts longer and looks tidier; wood chip is cheaper for large areas and breaks down faster, feeding the soil sooner.
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