Pixel to MM equation?

tl;dr: If you don't know the DPI of the device, you won't be able to deduce how big the pixel is in the real-world.

Pixels on their own are not real-world units of measurement.

They can become a real-world measurement if you take into account the DPI value of the device that displays them.

The formula is:

So 8 pixels viewed on a 96-DPI screen setting:

All this assuming the device is not scaled/zoomed.

What i did :

 <div id="my_mm" style="height:100mm;display:none"></div>

Then:

var pxTomm = function(px){   
   return Math.floor(px/($('#my_mm').height()/100)); //JQuery returns sizes in PX
 };

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