Calculate Flower Pot Volume
Want to know how much potting soil you need for a flower pot? This calculator makes it easy to calculate the volume in litres. Enter your pot’s dimensions, such as height and diameter, to see straight away how many litres of potting soil you need.
Calculate flower pot volume – how much potting soil do you need?
Want to know how much potting soil you need for a flower pot or planter? This handy tool makes it easy to calculate the volume of your pot in litres. This helps you avoid buying too little or too much potting soil. Whether you have a round flower pot, a tapered pot or a rectangular planter, the right dimensions will tell you exactly what you need.
Most flower pots do not have their capacity in litres stated on the packaging. That is why it is useful to calculate the volume yourself based on the dimensions. By entering the height and diameter (or length and width), this calculator automatically works out how many litres of potting soil you need.
How do you calculate the volume of a flower pot?
The volume of a flower pot is calculated based on its shape. The most common type of flower pot is slightly tapered, meaning that the top is wider than the bottom. In this case, it is a truncated cone. For straight-sided pots, use the cylinder formula, while for planters, a simple length × width × height calculation is used.
Our tool does this automatically for you. Simply enter the correct measurements in centimetres, and the calculator converts them into litres of potting soil.
How many litres of potting soil do you need?
The result of the calculation is shown in litres. This is the exact amount of potting soil needed to fill the pot completely. In practice, it is wise to take a few factors into account:
- Drainage layer: a layer of clay pebbles is often placed at the bottom of the pot. This means you need around 10% less potting soil.
- Air and root space: plants need room to grow, so it is sensible to round up slightly.
- Bags of potting soil: potting soil is sold in different bag sizes. Select the bag size you want to use in the calculator.
This tool immediately shows you how many bags of potting soil you need, so you can buy just the right amount.
Examples
- A flower pot measuring 30 cm high with a diameter of 30 cm holds approximately 21 litres of potting soil.
- A large planter measuring 80 × 30 × 30 cm has a volume of 72 litres.
- A tapered pot has slightly less volume than a straight-sided pot with the same top dimensions.
Calculating this in advance helps you avoid unnecessary costs and carrying extra bags.
Why use this tool?
- ✔ Quickly and easily calculate volume in litres
- ✔ Suitable for several flower pot shapes
- ✔ Instantly see how much potting soil you need
- ✔ Includes a calculation of the number of bags required
- ✔ Useful for gardens, balconies and houseplants
Frequently asked questions
How accurate is the calculation?
The calculation is very accurate as long as you enter the correct dimensions. Small differences in shape or rim thickness usually have little effect.
Do I need to fill the pot completely?
No, a drainage layer is often used at the bottom. This means you need slightly less potting soil.
What if my pot has an unusual shape?
Choose the shape that is closest to it. In most cases, this will give a good estimate.