Soil Calculator Guide: How Much Soil Do I Need?
Calculate garden soil volume for raised beds and planting areas, convert cubic metres to litres and understand finished depth and settling.
Garden soil is commonly sold by volume. Start with the area of the bed and the finished depth you want, then multiply them to get cubic metres. For raised beds, measure the internal fill dimensions and remember that loose soil can settle after delivery and watering.
Measure the bed
Measure the length and width of the actual fill area. For an irregular bed, split it into simple rectangles and add the areas.
Choose a finished depth
Use the depth you want after the bed is prepared. If compost, mulch, drainage material or existing soil occupies part of the bed, account for those layers separately.
Convert to cubic metres
Multiply area by depth in metres. One cubic metre is 1,000 litres.
Allow for settling
Soil products vary in moisture, texture and bulk density. A supplier may recommend a different quantity when settling or compaction is expected.
Formula
Soil volume = length × width × depth in metres.
Worked example
A 4 m × 2 m bed at 0.30 m depth is 2.4 m³, or 2,400 litres.
Common mistakes to avoid
- Using outside dimensions when the internal fill volume is smaller.
- Entering centimetres without converting to metres.
- Ignoring settling or other layers in a raised bed.
- Assuming every soil product settles in exactly the same way.
Frequently asked questions
How deep should garden soil be?
The appropriate depth depends on the plants and bed design. Use the finished depth you actually plan to fill and follow relevant gardening guidance.
How many litres are in a cubic metre of soil?
One cubic metre is 1,000 litres.
Does the calculator allow for settling?
No. It provides the geometric volume; settling depends on the product and conditions.
Use the Soil Calculator
Enter your project measurements in the calculator, review the result and compare it with the product or supplier information for your specific project.