Raised bed soil calculator
Work out how much soil you need to fill your raised beds, in cubic feet, cubic yards and bags, with the mix to use.
You need
- Cubic yards
- Bags
Suggested mix
Estimates only.
How this calculator works
Enter the length and width of your bed in feet, the soil depth in inches and how many beds you have. The calculator works out the total volume in cubic feet and cubic yards, and the number of bags in the size you choose.
The soil mix
For most beds, fill with about 60% quality topsoil and 40% compost. The calculator shows how much of each you'll need. Mix them together as you fill, or buy a ready-made raised-bed mix instead.
Tips
- Buy about 10% extra. New soil settles, often by an inch or two in the first season.
- Bulk is cheaper for several beds. Landscape suppliers sell soil and compost by the cubic yard.
- Top up each year with an inch or two of compost to replace what settles and feed the soil.
Common questions
A common mix is about 60% quality topsoil and 40% compost, or a ready-made raised-bed mix. Avoid filling beds with plain potting mix, which is expensive and drains too fast in large beds, or heavy clay garden soil.
Most vegetables and flowers grow well in 8 to 12 inches of soil. Deep-rooted crops like tomatoes and carrots do best with 12 inches or more. If the bed sits on open ground, roots can grow down into the soil below.
For very deep beds, some gardeners fill the bottom with logs, branches or leaves to save soil. These break down over time, so the bed will sink and need topping up.