Font Size Calculator
Convert font sizes between px, rem, em, pt, and vw. All conversions update live with copy buttons for each unit and correct DPI handling.
How to use
- Enter a value and choose its unit.
- Set the root font size (default 16px, matches browser default).
- Click any output value to copy it to your clipboard.
Frequently asked questions
What is the difference between em and rem?
em is relative to the parent element's font-size, while rem is relative to the root html element's font-size. rem is generally safer for consistent global sizing.
Should I use px or rem?
rem is preferred for accessibility because it respects user browser font-size settings. px ignores user preference, which can harm readability.
How do I convert pt to px?
1pt equals 1.333px at 96 DPI. Multiply pt by 4/3 to get px. The calculator handles this automatically.
How are viewport units calculated?
vw is a percentage of the viewport width. This calculator assumes a 1440px reference viewport for conversion display.