How to use this mulch calculator
- Units, choose Feet or Metres for your bed measurements.
- Length and width, enter the dimensions of your rectangular bed.
- Depth, enter how thick you want the mulch layer (inches in Feet mode, centimetres in Metres mode).
- Bag size, enter the size of the bags you plan to buy in cubic feet (a standard bag is about 2).
- Read the cubic yards, cubic feet and bags needed, they update instantly as you type.
Nothing is submitted or stored: the numbers never leave your device, so you can plan your beds privately.
How to calculate mulch
Mulch is sold by volume, so the calculation is simply volume = area × depth. First find the area of the bed by multiplying length by width, then multiply by the depth to get the volume. The trick is keeping your units consistent: depth is usually given in inches or centimetres, so it has to be converted to the same unit as length and width before multiplying. In Feet mode this calculator divides the depth in inches by 12; in Metres mode it divides the depth in centimetres by 100, then converts the result to cubic feet.
From there the conversions are fixed. 1 cubic yard = 27 cubic feet, so the calculator divides the total cubic feet by 27 to give cubic yards, the unit bulk mulch is usually sold in. A standard bag holds about 2 cubic feet, so to find bags it divides the total cubic feet by your bag size and rounds up, since you can only buy whole bags. A layer of 2 to 3 inches is typical for most beds, deep enough to hold moisture and slow weeds without smothering roots.
Note: This calculator assumes a rectangular bed and a flat, even layer. Real beds settle and ground is rarely perfectly level, so it is wise to buy a little extra. The bag figure is rounded up to the nearest whole bag.
Frequently asked questions
How much mulch do I need for my garden bed?
Multiply the bed length by the width to get the area, then multiply by the depth to get the volume. For a 10 ft by 10 ft bed at a 3 inch depth, that is 100 sq ft times 0.25 ft, or 25 cubic feet, which is just under one cubic yard.
How many cubic feet are in a cubic yard?
One cubic yard equals 27 cubic feet. So if your bed needs 54 cubic feet of mulch, that is 2 cubic yards.
How many bags of mulch are in a cubic yard?
A standard bag holds about 2 cubic feet. Since a cubic yard is 27 cubic feet, you need roughly 13.5 bags to make one cubic yard.
How thick should the mulch be?
A layer of 2 to 3 inches is typical for garden beds, deep enough to hold moisture and suppress weeds without smothering plant roots.
Is my data uploaded?
No, everything is calculated on your device and nothing is sent anywhere.