Raised Bed Soil Calculator
Enter a raised bed's length, width, and fill depth, and it works out the soil volume in cubic feet and yards — plus how many bags to grab at the store.
Bagged garden soil usually runs 1.5 cu ft a bag. Once you're filling more than a few beds, buying by the cubic yard gets a lot cheaper.
How it works
Volume is length times width times depth. Your bed's sides are in feet but the depth is in inches, so we divide the depth by 12 first — an 8-by-4 bed filled 10 in deep comes to about 26.7 cubic feet.
Bulk soil sells by the cubic yard, and a yard is 27 cubic feet, so we divide by 27. That same bed is right around one cubic yard, which is a handy number when you're calling a supplier.
Prefer bags? Bagged garden soil usually holds 1.5 cubic feet, so we divide the volume by 1.5 and round up. Bags are easy for one bed; by the yard wins once you're filling several.
Frequently asked questions
How deep should a raised bed be?
Six inches works for greens and herbs, but most vegetables are happier with 10 to 12 in of root room. Deep-rooted crops like carrots and tomatoes especially appreciate the extra depth.
How many bags of soil fill a raised bed?
Depends on the bed, but a common 8-by-4 bed filled 10 in deep needs about 18 bags of the 1.5-cubic-foot size. The tool counts the exact number for your dimensions.
Should I fill it all with bagged soil?
You can, but it adds up fast. Many gardeners fill the bottom third with compost, leaves, or coarse material and save the bagged soil for the top, where the roots do most of their work.
Do I need to account for settling?
A bit — fresh soil and compost settle over the first few weeks. Fill slightly proud of the rim, or plan to top off with a bag or two once things pack down after watering.