About the Pot Volume Calculator
Compost needed to fill plant pots of any shape and size.
Also known as: plant pot size calculator, container volume, how much compost for a pot, planter capacity.
How to use this calculator
- Enter pot shape, height, number of pots and the other fields.
- The result updates instantly as you type — press Calculate (or Enter) at any time.
- Review the breakdown shown under the main result.
- Use Copy result or Share to save the answer or send a link with your inputs.
Formula
Tapered pot: V = πh(r₁² + r₁r₂ + r₂²) ÷ 3
Worked example
Using the values pre-filled in the calculator above:
- Pot shape: Round (tapered)
- Top diameter = 30 cm
- Base diameter = 22 cm
- Height = 28 cm
- Number of pots = 6
the calculator returns:
- Pot volume: 14.98 litres
- Compost per pot: 13.48 litres
- Total compost needed: 80.9 litres
- 50 litre bags: 2