Math CentralQuandaries & Queries


Question from MJ:

I need help in figuring out how much mulch to buy....I either over buy or under buy.

I have an area that is 35' X 50' and I want to cover it with 2" of mulch.

Do I take length X Width X depth? Bags of mulch are sold in 2 or 3 cubic feet per bag.....I just want to know how to do the math. can you please send me the equation?




Length times width times depth is exactly what you wan but first you need the three dimensions in the same units. The bags of mulch are labeled in cubic feet so you need all three dimensions in feet. The length and width are already in feet but the depth is in inches. There are 12 inches in a foot so 2 inches is 2/12 feet. Hence the volume of mulch you need is

35 × 50 × 2/12 = 291.67 cubic feet.

If you buy 3 cubic foot bags you will need 291.67/3 = 97.2 bags.

To find the volume you could also use our volume calculator.


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