Filling a raised bed with the wrong amount of soil wastes money and trips to the garden center. Our free soil calculator takes the guesswork out of the process.
Enter your raised bed dimensions, choose a shape (rectangular, circular, or L-shaped), and select a soil mix. The calculator gives you the exact volume in cubic feet and cubic yards, plus an estimated cost breakdown for topsoil, compost, and amendments.
The default 60/30/10 mix (topsoil, compost, perlite or vermiculite) follows extension service recommendations from University of Minnesota Extension for productive raised bed growing.
Frequently Asked Questions
How much soil do I need for a 4×8 raised bed?
A 4×8 foot raised bed that is 12 inches deep needs approximately 32 cubic feet (1.2 cubic yards) of soil. Our calculator gives you the exact amount based on your specific dimensions and depth.
What is the best soil mix for raised beds?
A mix of 60% topsoil, 30% compost, and 10% perlite or vermiculite provides excellent drainage and nutrients. This follows recommendations from university extension services for vegetable and flower gardening.
How deep should a raised bed be?
Most vegetables need at least 12 inches of soil depth. Root vegetables like carrots and parsnips prefer 18-24 inches. Herbs and lettuce can grow in beds as shallow as 6-8 inches.
Should I put anything at the bottom of a raised bed?
Place cardboard or landscape fabric at the bottom to suppress weeds. Do not add rocks or gravel — this creates a perched water table that impedes drainage rather than improving it.
How do I calculate soil for a round raised bed?
Use the formula: pi × radius² × depth. Our calculator handles circular beds automatically — just enter the diameter and depth to get the volume in cubic feet and cubic yards.