Reference Designer Calculators

mm to thou calculator

PCB Designers often need to work on metric as well as inches and thou. Thou stands for one thousandth of an inch and is called mils in US. We are presenting the formula and calculator for converting thou to mm and vice versa.

The formula for thou to mm conversion goes as follows.

mm = thou x 2.54

To make it easy to remember - every 100 thou is equivalent to 2.54 mm. Look at he equation again and memorize it - you will need it often, if you are working on PCB design and footprints.
If thou = 100
mm = 100 x 2.54

The formula for mm to thou is simply the reverse .

thou = mm x 100

Again to memorize is ( and for intuition), keep in mind that for every 2.54 mm you get 100 thou. Eevery 1 mm is 39.37 thou and if you just want a close value for intuition, you may use rough value for each mm as 40 thou.

You can use the calculator below to covert mills into mm and vice verso. Enter the value in thou and hit the mm button to convert mm to Mil and vice versa.

  Thou :