Font Size Converter Free Online
Convert CSS font sizes between px, em, rem, pt, and % using a configurable base font-size (default 16px = 1rem = 100% in browsers). All units shown side-by-side.
Results
Pro — bulk batch calculation, API access, history & favorites
API access · Priority queue · Team workspace
Related Tools
Font Size Converter Features
5 CSS Units
px (absolute), em (parent-relative), rem (root-relative), pt (print), and % (relative). Plus pc (pica) bonus.
Web & Print
px and rem dominate web; pt is print/Office; em is component-relative for accessibility (scales with user font-size preference).
Configurable Base
Default 16px = browser default. Change to 14px, 18px, or any value to match your design system or user font preference.
Live Conversion
Type any value, all units update instantly.
Reference Values
1pt = 1/72 inch = 1.333 px. 1pc = 12pt = 16px. 1em/rem at 16px base = 16px = 12pt = 100%.
100% Private
All math runs in your browser.
Free vs Pro
| Feature | Free | Pro |
|---|---|---|
| Full font size calculation | ||
| Live calculation | ||
| All-units result panel | ||
| Bulk batch calculation | — | |
| REST API access | — | |
| Save & share calculations | — |
Frequently Asked Questions
em = px ÷ base (parent or root font-size). With default 16px base: 24px = 1.5em. With 18px base: 24px ≈ 1.333em.
em is relative to the parent element's font-size; rem is relative to the root (html) font-size. rem is more predictable; em compounds with nesting (problematic for components).
1pt = 1/72 inch. 1 CSS inch = 96 px (W3C standard). So pt × (96/72) = pt × 1.3333 = px. 12pt = 16px. 10pt = 13.33px.
16px in Chrome, Firefox, Safari, Edge. Users can change this in browser settings — a key reason to use rem/em (which respect user preference) over px (which does not).
Modern recommendation: use rem for typography and component sizing (respects user preference), em for component-internal spacing, % for layout widths, px for borders/shadows where you want pixel-perfect.