Raised Bed Soil Calculator
Filling a raised bed always takes more soil than it looks. Enter the bed’s dimensions to get the exact volume and the number of bags, so you don’t make three trips to the garden center.
Raised Bed Soil Calculator
Why use the Raised Bed Soil Calculator
Raised beds always swallow more soil than they look. This prevents the half-full-bed surprise.
How to get your numbers
- Inside length & width in feet.
- Fill height in inches.
- Deep beds: fill the bottom with bulk material to save on premium mix.
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How to use it
- Enter the inside length and width in feet.
- Enter how deep you’ll fill it, in inches.
- For big beds, fill the bottom third with cheaper bulk material to save on premium mix.
Frequently asked questions
How much soil do I need for a raised bed?
Multiply length × width × height (all in feet) for cubic feet. A 4×8 bed filled 12 inches deep needs about 32 cubic feet.
What is the best soil mix for a raised bed?
A common blend is roughly 60% topsoil, 30% compost and 10% aeration such as perlite or vermiculite.
How can I save money on raised-bed soil?
For deep beds, fill the bottom third with logs, branches, or leaves (a “hügelkultur” base) and top with quality growing mix.
How deep should a raised bed be for vegetables?
At least 10–12 inches for most vegetables; root crops and deep feeders like tomatoes appreciate 18 inches or more.
Topsoil, garden soil, or potting mix for raised beds?
Use a raised-bed or garden-soil blend, not straight potting mix (too light and expensive) or bagged topsoil alone (too dense). Amend with compost.
How many bags of soil for a 4×8 raised bed?
About 32 cubic feet at 12 inches — roughly 21 bags of 1.5 cubic feet. Adjust for your fill depth above.
Do I need to refill raised beds every year?
The level drops as organic matter breaks down, so top up with a couple of inches of compost each season rather than a full refill.
