Potting Mix Calculator
Calculate how much potting mix or compost is required for round pots and rectangular containers.
90.9 litres
0.091 m³
2 bags
How the calculator works
Round pots are calculated as cylinders, while rectangular planters use length multiplied by width and depth. Quantities are multiplied by the number of containers.
A small settling allowance can be included to reduce the chance of running short after watering in.
Frequently asked questions
How much compost do I need for a pot?
Pot volume depends on diameter and depth for round pots, or length, width, and depth for rectangular planters.
How do I calculate litres for a round pot?
Use cylinder volume: pi × radius squared × depth, then multiply by 1,000 to convert cubic metres to litres.
Should I add extra potting mix for settling?
A small allowance is helpful because fresh compost can settle after watering. Around 5% extra is often enough.
What size compost bags are common?
Common bag sizes include 40 L, 50 L, 60 L, and 70 L. Choose the same bag size in the calculator for accurate estimates.