Charts
Raised Bed Soil Chart
Quick Answer
A 4 ft x 8 ft bed filled 12 inches deep needs 32 cubic feet of soil, or about 16 bags if each bag contains 2 cubic feet.
Practical Guide
Raised bed soil charts are helpful for common sizes, but the most accurate estimate uses inside bed dimensions. Lumber thickness and actual fill height can change volume.
Plan for settling and leave some room below the top edge for watering, compost, and mulch.
How to Use the Chart
Find the bed size and fill height closest to your project. If your bed is a different size, multiply length by width by height in feet.
Formula
Length feet x width feet x height feet x number of beds x fill level = cubic feet.
| Bed size | 12 inch fill | 18 inch fill | 2 cu ft bags at 12 inch fill |
|---|---|---|---|
| 3 ft x 6 ft | 18 cu ft | 27 cu ft | 9 bags |
| 4 ft x 4 ft | 16 cu ft | 24 cu ft | 8 bags |
| 4 ft x 8 ft | 32 cu ft | 48 cu ft | 16 bags |
| 4 ft x 10 ft | 40 cu ft | 60 cu ft | 20 bags |
FAQ
How much soil does a 4 by 8 raised bed need?+
At 12 inches deep, it needs 32 cubic feet. At 18 inches deep, it needs 48 cubic feet.
How many cubic feet are in a cubic yard?+
There are 27 cubic feet in one cubic yard.
What fill level should I use?+
Many gardeners use 80% to 90% fill to leave room for watering, compost, mulch, and settling.
What mix should I use?+
A simple planning mix is 60% topsoil, 30% compost, and 10% aeration material, adjusted for local needs.