Metric Cubic Soil Volume Calculator: How Much Soil Do I Need?

Whether you’re a seasoned pro or a weekend warrior, accurate soil measurements can make all the difference.

Gardening is more than a hobby; it’s an art and a science. Knowing how much soil you need for different gardening tasks can make or break your project.

This article dives into four key areas: filling raised beds, potted plants, garden beds, and top soil. We’ve included a handy soil calculator in each section to help you estimate soil volume in cubic metres.

Raised Bed Soil Calculator

Raised garden bed 1 | Plant care

Raised beds are a gardener’s dream for many reasons, including better drainage and soil quality. However, the wrong soil volume can lead to poor plant growth, waterlogging, or even soil erosion.

Calculating Soil Volume for Raised Beds

To calculate the soil volume for a raised bed, measure its length, width, and depth in metres. Multiply these dimensions together to get the volume in cubic metres. This is the amount of soil you’ll need to fill the bed adequately.

Once you’ve got your cubic metre calculation, you can easily convert this to potting mix bags if you need to.

For example, if a bag contains 25 litres of soil, and you need 1 cubic metre, you’d need 40 bags since 1 cubic metre equals 1,000 litres.


When it comes to soil types, a mix rich in organic matter is often the best choice for raised beds. This type of soil not only retains moisture well but also allows for good drainage, offering your plants the best of both worlds.

Potted Plant Soil Calculator

dahlia in pot 2 | Plant care

The volume of soil in your pots directly impacts the health of your plants. Too little soil means inadequate room for root growth, while too much soil can leave you with an unwanted surplus.

Calculating Soil Volume for Planters

For cylindrical pots, here’s a simple way to calculate soil volume:

  1. Measure across the top of the pot to find the diameter. Then, divide that number by 2 to get the radius.
  2. Measure how deep the pot is.
  3. Multiply the radius by itself.
  4. Then multiply that number by 3.14 (which is a number called pi).
  5. Finally, multiply that result by the depth of the pot.

The calculator below does this for you.

For square or rectangular pots, the formula is length × width × height, so you can use the raised bed calculator above.

For potted plants, you’ll likely need less soil than for other projects. If the calculator says you need 0.05 cubic metres, that’s 50 litres. So, you’d need two 25-litre bags.


The type of soil you choose should complement the needs of your specific plants. For instance, succulents prefer a sandy, well-draining soil, whereas most houseplants are happy with a more balanced, moisture-retaining mix.

Garden Bed Soil Calculator

vegetable garden 3 | Plant care

Your garden beds are essentially the stage upon which your plants perform. The right soil volume is critical for robust plant development and overall garden health.

Calculating Soil Volume for Garden Beds

Much like raised beds, you’ll need to measure the length, width, and depth of your garden bed in metres. Multiply these dimensions together to find out how many cubic metres of soil you’ll need.

For garden beds, you’ll likely be buying in bulk, which is usually quoted in cubic metres. So, if the calculator says you need 2 cubic metres, you can directly use this figure when ordering your bulk soil.


Soil type can make a significant difference here. For flower beds, a loamy soil usually works best. If you’re planting vegetables, a soil mix rich in compost can provide the nutrients your plants crave.

Topsoil Calculator

top soil 1 | Plant care

Topsoil is the uppermost layer of soil and is vital for lawn or plant growth. Applying the right amount can significantly improve your garden’s fertility and structure.

Calculating Top Soil Volume

To calculate the amount of topsoil you’ll need, measure the area you intend to cover. Multiply this by the depth of topsoil you plan to apply. This will give you the volume in cubic metres.

For topsoil, bulk purchases are common and are quoted in cubic metres. If you need 4 cubic metres, you can use this exact figure when ordering your soil in bulk.


For most gardens, a balanced topsoil rich in organic matter is ideal. It improves water retention and provides essential nutrients, making it a versatile choice for various plants.

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Steve Kropp

Based in Melbourne, Steve's passion is vegetable gardening, and he’s been writing about it for almost 5 years. He also loves all things DIY and is always looking for a new project. When not working on his own garden projects or blogging, Steve enjoys spending time with his family, cooking meals with produce harvested from his garden, and coaching his son’s footy team.


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