Mulch Calculator
Work out how many cubic yards or bags of mulch you need from bed size and depth, in imperial or metric units.
Last reviewed by the Radiatus Cloud team
Recommended depth: 2–3″ for flower beds, 3–4″ around trees and shrubs. Keep mulch a few inches away from trunks and stems.
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Work out how much mulch you need
Mulching a garden bed needs the right amount, and buying by guess wastes money or falls short. This calculator works out the cubic yards or bags of mulch needed from your bed size and desired depth.
Why depth is the key variable
Mulch is spread to a depth, and the volume needed is the bed area times that depth, so depth matters as much as area: doubling the depth doubles the mulch. Too thin and it does not suppress weeds or retain moisture; too thick can harm plants. Working out the volume from the area and a suitable depth, then converting to cubic yards or the number of bags, gives the quantity to buy, which avoids the trips back and forth that guessing causes.
A planning estimate
These are estimates from a standard method for general planning, not professional advice; confirm anything important for your specific situation. It runs entirely in your browser, so nothing you enter is uploaded and it works without an account, keeping your figures on your own machine.
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Frequently Asked Questions
How is mulch quantity calculated?
As the bed area times the desired depth, giving the volume, converted to cubic yards or the number of bags to buy.
Why does depth matter?
Because volume is area times depth, so depth affects the quantity as much as area. Too thin fails to suppress weeds; too thick can harm plants.
What depth of mulch is typical?
A few inches is common for weed suppression and moisture retention, though it varies by mulch type and purpose. The calculator uses the depth you set.
Should I buy in bulk or bags?
Bulk cubic yards are cheaper for large areas; bags suit small ones. The calculator gives both so you can choose.
Is my data uploaded?
No. The calculation runs entirely in your browser.
Privacy & Security
Runs entirely in your browser. No data is sent to any server.
How to Use
Enter your bed's length, width and desired mulch depth, choose a bag size, and see cubic yards, cubic metres and bags to buy.
Disclaimer: This tool is provided "as is" without warranty of any kind. Results are for educational and utility purposes.
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