Raised Bed Soil Calculator
Find how much soil fills a raised garden bed.
Default 1.5 cu ft
Results update as you type.
How it works
Filling a raised garden bed takes more soil than most people expect, and this calculator tells you exactly how much so you order the right amount in one trip. You enter the bed's length and width in feet, the fill depth in inches, and optionally the size of the bags you plan to buy, and it returns the volume in cubic feet, cubic yards, and liters, plus the number of bags needed. The math is straightforward volume: length times width times depth, with depth converted to feet. Cubic yards matter because bulk soil is usually sold by the yard, while bagged soil and compost are sold in cubic-foot bags, so the calculator gives both. A common approach is to fill beds with a blend, such as topsoil, compost, and a lightweight amendment like peat or coco coir, so you can split the total volume among components. Remember that fresh soil settles over the first season, so filling slightly above the target depth or topping up later is normal. For deep beds you can also save soil and improve drainage by adding coarse material at the very bottom. Enter your bed dimensions and depth to see how much soil to buy.
Volume = length × width × depth; bags = volume ÷ bag size
The soil volume is simply the bed's length times its width times the fill depth, with the depth converted from inches to feet. Dividing that cubic-foot volume by the size of each soil bag, then rounding up, gives the number of bags you need to fill the bed.
Source:Volume geometry
We review all our tools from time to time to ensure accuracy.
Worked example
How to use this calculator
- 1
Enter your values
Enter bed length, bed width and fill depth.
- 2
Adjust the options
Adjust bag size if they apply — sensible defaults are already set.
- 3
Read your result
Soil volume updates instantly as you type — no button to press.
Frequently asked questions
How much soil do I need for a raised bed?
Multiply the bed's length by its width by the fill depth, keeping units consistent. An 8-by-4-foot bed filled 12 inches deep needs 32 cubic feet, a little over a cubic yard. The calculator converts to cubic feet, cubic yards, and liters and estimates bags, so you can buy either bagged or bulk soil confidently.
Should I buy bagged or bulk soil?
For small beds, bagged soil is convenient and easy to carry, though it costs more per volume. For larger projects or several beds, bulk soil delivered by the cubic yard is much cheaper. As a rough guide, once you need more than about ten to fifteen bags, bulk delivery usually becomes the better value despite the delivery fee.
What is a good soil mix for raised beds?
A popular blend is roughly equal parts quality topsoil, compost for nutrients, and a lightweight material like peat moss or coconut coir for moisture retention and drainage. This gives fertile, well-draining soil that plants love. You can split the total volume this calculator gives among the three components to know how much of each to buy.
Why does raised bed soil settle?
Fresh soil and compost contain air pockets and organic matter that compress and decompose over time, so the level drops during the first growing season. It is normal to lose an inch or two of height. Filling slightly above your target depth at the start, or topping up with compost each season, keeps the bed full and productive.
Can I put anything at the bottom to use less soil?
Yes. For deep beds, filling the bottom few inches with coarse material such as small logs, branches, straw, or wood chips reduces how much soil you need and improves drainage. This technique, sometimes called hügelkultur when using wood, also adds organic matter as it breaks down. Just keep enough real soil on top for root depth.