Potting Soil Calculator

Created by Hanna Pamuła, PhD candidate
Reviewed by Bogna Szyk and Adena Benn
Last updated: Aug 26, 2022

This potting soil calculator allows you to measure the volume of soil needed for your container. Whether you want to have a raised bed in your garden or rearrange your blooming balcony, use the calculator to estimate how much soil you need to prepare. Choose from three types of containers, calculate your needs, then go ahead and start your garden!

Container shape

There are many different container types on the market. In our potting soil calculator, you can select between three different shapes. It finds the volume according to the formulas below:

  • rectangular - e.g., raised bed soil containers

    volume of rectangular cuboid: volume = depth * length * width

  • round

    volume of a cylinder: volume = π * R² * depth , where R is a radius

  • flower pot in the shape of a truncated cone

    volume of a truncated cone: volume = (1/3) * π * depth * (r² + r * R + R²), where r is a radius of the base of flower pot, and R of top surface radius

If you want to estimate the weight or cost of topsoil, use our soil calculator.

How much soil do I need?

Let's imagine that you want to grow herbs. You have a couple of small flower pots, and you don't know how much soil you need. This potting soil calculator can help with that problem:

  1. Choose the shape of the container.
    In our case, it's a flower pot, so we need to calculate the volume of the truncated cone.
  2. Enter the dimensions.
    For example, assume we have pots with a diameter across the top equal to 4 inches, a bottom base diameter of 3.2", and a height of 2.75". Don't forget that you can select different units, such as centimeters, feet, etc.
  3. Set the quantity of the flower pots.
    We want to plant oregano, basil, and thyme, so we need to put three in the quantity field.
  4. The volume of soil required is equal to the displayed value.

Our calculator is a flexible tool, so you can calculate everything the other way round: if you have a bag of soil and the size of your containers, you can estimate how many pots can be filled.

Remember that the obtained result represents the volume for the full container. Sometimes you want to fill the container to 4/5, or you already have a plant or tree with the roots, and then you will need less soil. The amount of soil may also change as you squeeze it or leave it looser, so the presented calculations are only a good estimate.

Are you interested in other agricultural calculators? Check out our vegetable seed and fertilizer calculators.

Hanna Pamuła, PhD candidate
US qt
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