🔤 Typography Unit Converter (px/pt/em/rem)
Edit any field and the rest update instantly. rem is always relative to the root (<html>) font size; em is relative to its own element's parent font size — set both below to match your actual CSS.
Reference sizes
What 1
rem equals. Browser default is 16px unless overridden.
What 1
em equals for the element you're sizing. em compounds with nesting — this is only the immediate parent.
CSS defines 1in = 96px at "reference pixel" density — this is the standard assumption, not your monitor's real DPI.
Convert
Physical size (inches)
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Physical size (mm)
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"Physical size" assumes the CSS reference pixel convention (96px = 1 inch at 100% zoom on a typical
display) using the DPI above — it's a useful approximation for print/design planning, not a guarantee of
the size on any specific physical screen, since real pixel density varies by device.