Before you calculate how much bark mulch you need, you should think about how high you want to cover the ground with bark mulch. The recommended height is about 7-8 cm so that the mulch has a good effect against weeds.
Once you know the height of your mulch, you can calculate how many square metres of bark mulch you will need.
The average is 10 litres per square metre at a height of 1 cm. In our example, at a height of 7 cm, it would be 70 litres per square metre and thus about 20 kilograms per square metre.