Pixels, EMs *, Percents *, Points. 6px, em, %, 5pt. 7px, em, %, 5pt. 8px, em, 50%, 6pt. 9px, em, %, 7pt. ppm to percent number conversion: calculator and how to convert. Just like em's the very nature of percentage sizing is that it is relative. It also cascades in the same way, so the very problem described above of. December 14, at 3: I wish there were a definitive right way to do things… sigh. Em to percent the best cross-browser and cross-platform results while printing pages, set up a print stylesheet and size all fonts with point sizes. July 11, at 2: The once daunting challenge of converting pixels px to the elusive em has now been reduced to a booger eating pipsqueak.