This calculator will help determine how much soil you will need for a raised bed, and will break down the results into recommended soil ratios so that you can decide whether to buy your soil in bags or by the yard.
Results are provided in both the amount of raised bed soil to buy as well as a breakdown of the different soil types if you are going to do it yourself.
What’s The Average Depth Of A Raised Bed
The average depth of a raised garden bed is 11 inches (two 2×6 boards) and is 4 feet wide by 8 feet long. This is the minimum depth needed for vegetables such as cucumbers and tomatoes.
How Much Soil Do I Need For a 4 Foot By 8 Foot Raised Bed
You would need roughly a total of 29 cubic feet of soil (or 1 cubic yard), which would require 39.11 .75 cu. ft. 40 pound bags of soil for a 4 x 8 raised garden bed at 11 inches deep.
For a 4 foot by 4 foot raised vegetable bed you would need a total of 14.67 cubic feet of raised bed soil, or 9.78 1.5 cu. ft. bags of raised bed soil.
Use the calculator to find the soil amount needed for you bed, as well as a breakdown of soil ingredients if you plan to make your own raised bed soil.
What’s The Best Soil To Use In A Raised Bed
At a minimum, it’s best to use a mix of 60% topsoil and 40% garden soil in a raised bed if you aren’t using raised bed soil. If you were to only use garden soil, which is rich in compost, it could result in the vegetable bed holding water longer and possibly leading to fungus and root rot. Topsoil alone would be too dry and lack nutrients.
The ideal raised bed soil mix recipe would be to used 60% topsoil, 30% garden soil, and 10% potting soil.
DIY Raised Bed Soil Mix Recipe
The calculator will give you a breakdown of the quantities to purchase each soil type in 1.5 cu. ft. bags.
What is the difference between garden soil and raised bed soil?
Garden soil is a compost rich soil that is not intended to be used on its own; it is added to existing soil. Raised bed soil is a pre-mixed soil that contains the proper ratios of topsoil, garden soil, and non-soil ingredients (peat moss, sphagnum moss, perlite, vermeculite, etc)
For reference:
- One cubic yard equals 27 cubic feet.
- A 40 pound bag of soil usually contains about .75 Cubic Feet of soil.
- A 40 pound .75 cu. ft. bag of soil is enough to cover a 9 square foot area at 1 inch deep.
- There are 37.5 40 pound .75 cu. ft. bags of soil are in a cubic yard.
- There are 25.71404638 Dry Quarts in a Cubic Foot, so a 25 quart bag of potting soil would equal approximately 1 Cubic Foot.
