Get Width of element and Increment

Get Width of element and Increment

Hi, i need help with getting the width of an element and displaying a value. Basically i have a customer who is building a sign making websites. The sign is just text based but the pricing side is based on the width of the sign. So far i have worked out that every 32px is 5cm.

The input field auto resizes based on the text within it. but i need to display on the site the size i.e if its 32px it shows 5cm then every 32pixels it updates in 5cm increments. 5cm (32px), 10cm (64px), 15cm(96px) etc...

Is this possible? if so what's the best way to accomplish it? I have a very tiny bit of jquery knowledge but am no where near confident enough to know how to pull this off.

Your help is very much appreciated.