Font size converter
Convert px, em, rem and pt with your chosen base size.
Font size converter (px, em, rem, pt)
Convert font sizes between px, em, rem and pt using a configurable base size (16 px by default). Built for CSS, web design and layout.
How they relate
em = px / base · rem = px / base · pt = px × 0.75
With a 16 px base: 1 em = 1 rem = 16 px; 12 pt = 16 px. em is relative to the parent element’s size and rem to the root (<html>), which is why rem is more predictable.
When to use each
- rem: consistent, accessible global sizing.
- em: scale relative to local context (buttons, icons).
- px: fixed details.
- pt: print (1 pt = 1/72 inch).
Frequently asked questions
How many px is 1 rem? 16 px by default, unless you change the root size.
And 1 em? It depends on the parent element’s size; with a 16 base, 1 em = 16 px.
pt vs px? At 96 dpi, 1 px = 0.75 pt and 12 pt = 16 px.