Mulch Calculator

Measure your bed, pick a depth, and this tells you how many cubic yards to order in bulk or how many bags to put in the trolley.

How the math works

Volume = length x width x depth, with every measurement in feet. Divide by 27 to get cubic yards, because a cubic yard is 3 x 3 x 3 feet.

How deep should mulch be?: Two to three inches is the usual answer for beds. Three inches suppresses weeds well. Going past four inches holds too much water against the soil and can suffocate shallow roots.
How many bags are in a cubic yard?: A cubic yard is 27 cubic feet, so it is 13.5 bags of the common two cubic foot size, or 9 bags of the three cubic foot size.
Should I buy bulk or bags?: Bags are easier for one small bed and need no delivery. Once you pass about three cubic yards, bulk delivery is normally cheaper per yard, though you need somewhere to tip it and a wheelbarrow.
Do I need to remove the old mulch first?: Not usually. Rake it flat, break up any matted crust, and top it up to the depth you want. Only strip it out if it has gone sour or mouldy.