Convert REM to EM
Rem and em resolve to the same pixel size when an element's font size equals the root, but they diverge the moment font sizes are overridden. This converter shows the equivalent em for a rem value at a shared base, and the live tool lets you compare all three units side by side.
0.5rem 1rem 1.5rem 2rem
0.5em 1em 1.5em 2em
Try it with your own data
How to convert REM to EM
- Start with your rem value, which is relative to the root font size.
- At a matching base font size, the numeric em value is identical.
- If a parent element changes the font size, recompute em against that size.
Frequently asked questions
Is 1rem always equal to 1em?
Only when the element's font size equals the root font size. Because em is relative to the current element and rem to the root, they drift apart inside resized or nested elements.
Which should I prefer?
Use rem for predictable global sizing and em when you want a value to scale with a specific element's own font size.
What is the difference between REM and EM?
rem (Root EM) is relative to the root element (usually the <html> element) font size. em is relative to the font size of its nearest parent element.
Why use REM instead of pixels?
Using rem units is crucial for accessibility. If a user changes their browser's default font size, your entire layout scales proportionally — something static pixel units can't do.