# Converting Inches to Centimeters

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Sometimes there is a need to know a length in centimeters, but all you have is the length in inches.

We know that in 1 in, there are 2.54 cm.

Method 1

Lets suppose you are 60 inches tall. How many cm tall are you?

Because 1 in = 2.54 cm, 60 inches can be converted to cm by multiplying 60*2.54= 152.4 cm.

How does that work? Well we can think of it as a proportion.

Using cross products, 1x=(2.54)(60) so x=152.4 cm.

Method 2

This method will work for any conversion that you need to make. We start with our unit that we have originally. Then we multiply by a "unit factor." A unit factor is a fraction that is really one, but doesn't look like it. For example, I know 1 foot = 12 inches so if I create a fraction (1 foot/12 inches), that is one, but gives us the ability to convert to other units.

I want to convert 5 inches to centimeters.

I start with the unit that I have and turn it into a fraction. Then I will multiply by the unit rate. The inches label will cancel because I have one in the numerator and one in the denominator. 