The calculation is simple
Multiply length by width by depth, then divide by 12 when the bed measurements are in feet and depth is in inches. This gives cubic feet. Multiply cubic feet by approximately 7.4805 to estimate US gallons. The tool uses those same conversions and rounds the display to two decimal places.
What this tool can and cannot tell you
- It estimates geometric volume for a level rectangular area; irregular beds can be divided into smaller rectangles.
- It does not decide an application depth for your soil, crop or product.
- It does not account for settling, compaction, moisture or material losses.
- It does not convert Soily pounds into gallons or coverage. That requires a verified bulk density that we have not published.
Use the number to ask a better buying question
Once you know the planned volume, compare suppliers using compatible units. Keep the base material for filling a bed separate from a small-bag amendment. If your project needs a large volume, a local bulk supplier may be the practical starting point. The default depth in the calculator is an example only, not an application recommendation.
Further reading
These references explain general growing practices. They are not tests or endorsements of Soily products.
Plan your next step
Plan amendment volume
Calculate volume for a layer over a rectangular bed. Choose a depth recommended by your soil test or the product label. This is a planning tool, not a Soily application rate.
Volume: 0.67 cubic feet / 4.99 US gallons
Soily bags are sold by weight. We have not verified bulk density, so this tool does not convert volume into bags.