About this calculator
How much mulch or bark you need for beds and borders, in cubic metres for bulk bags and 50, 70 or 100 litre bags.
How it’s calculated
Volume = area × depth. 1 m³ = 1,000 litres = 14.3 bags of 70 L.
Worked example
With these inputs:
- Area shape
- Rectangle
- Length
- 6 m
- Width
- 3 m
- Depth
- 75 mm
- Material
- Bark mulch
- Extra allowance
- 0%
the result is:
- Volume
- 1.35 m³
- Area
- 18 m²
- Approx. weight
- 540 kg
- 50 L bags
- 27 bags
- 70 L bags
- 20 bags
Tips from the trade
- 50–75 mm is the usual depth for weed suppression.
- Keep mulch a hand’s width clear of trunks and stems.
- Bulk works out cheaper than bags above about 1 m³.
Common questions
How many bags of bark in a cubic metre?
About 14 bags of 70 L, or 20 bags of 50 L.
Results are estimates for planning and pricing. Check quantities against your drawings, the manufacturer’s data and the Building Regulations before ordering.