Garden Soil Calculator
Work out how much soil a raised bed or several beds need from their size and fill depth, split into compost and topsoil, with bags and cubic yards. Calculates in your browser.
Soil needed
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Show the math
Volume is bed area times depth, multiplied by the number of beds:
cubic feet = length × width × (depth ÷ 12) × beds
compost = volume × compost %; topsoil = volume − compost
A common raised-bed mix is roughly a third compost to two-thirds topsoil or a soilless blend. Bulk by the cubic yard is cheaper for several beds. All math runs locally in your browser.
What this does
A garden soil calculator works out how much soil a raised bed or several beds need from their size and fill depth, split into compost and topsoil, with bags and cubic yards.
How to use it
- Enter the bed size and number of beds.
- Enter the fill depth.
- Set the compost percentage.
- Read cubic yards and bags.
How it works
Volume is the bed area times the fill depth. A common raised-bed blend is about a third compost to two-thirds topsoil.
cubic yards = area × depth (ft) ÷ 27
Understanding your result
The volume tells you how much to buy, where bulk cubic yards are usually far cheaper than bags for anything beyond a single small bed. A common raised-bed blend is about one third compost to two thirds topsoil, and soil settles, so slightly overfilling avoids a top-up later.
Example
A 4×8 ft bed filled 12 inches deep needs about 1.2 cubic yards of soil.
Sources & methodology
Last updated .
Frequently asked questions
What soil mix should I use?
A common raised-bed blend is roughly a third compost with two-thirds topsoil or a soilless mix; the tool splits your total by the compost percent you choose.
Bags or bulk?
Bulk soil by the cubic yard is usually cheaper once you need more than a few beds; bags are convenient for a single bed. The tool reports both.
How deep should a raised bed be?
Most vegetables are happy with 10–12 inches of good soil; deeper roots like carrots or parsnips prefer more.
Is anything stored?
No. Everything is calculated locally in your browser.
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