PX to REM/EM Converter
Convert CSS pixels to REM, EM, PT, and percent. Set your base font size and get accurate values for responsive design.
Bulk Conversion
About this calculator
Convert CSS pixels to rem, em, pt and percent, singly or as a list of values at once.
Responsive design works best in relative units, and designers hand over pixel sizes, so a converter saves mental arithmetic.
How to use it
- Set the base font size (16px by default).
- Type a value.
- Read the other units.
The formulas
rem = px ÷ root font-size. With the default root of 16px, 24px is 24 ÷ 16 = 1.5rem. em is relative to the parent element's font size, so it compounds when nested. pt = px × 0.75 (96 px per inch, 72 pt per inch). vw is 1% of the viewport width: on a 1440px screen, 1vw = 14.4px.
Worked example
With a 16px base
| 12px | 0.75rem |
| 16px | 1rem |
| 24px | 1.5rem |
| 32px | 2rem |
| 48px | 3rem |
Tips and common mistakes
- Use rem for font sizes so users' browser settings are respected.
- Use px for borders and hairlines.
- Use em for padding that should scale with the element's text.
- Avoid px-only layouts on mobile.
- Use clamp() for fluid type.
Frequently asked questions
How do I convert px to rem?
Divide the pixels by the root font size, normally 16.
What is rem?
A unit relative to the root (html) font size.
What is the difference between rem and em?
rem uses the root; em uses the parent.
How many pt in a px?
1px = 0.75pt.
What is vw?
1% of the viewport width.
Why use rem?
It respects the user's font-size preference.