CSS Unit Converter px rem em
Convert common CSS units for typography and layout.
rem1rem
em1em
%100%
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How is this result calculated?
CSS units such as px, rem, em and % describe relative or absolute sizes. px is fixed, rem depends on the root size, em depends on the parent.
rem and em conversions depend on a base. By default, many browsers use 16 px for 1 rem.
Frequently asked questions
What is the difference between rem and em?+
rem uses the root font size, while em uses the parent or current element font size depending on the property.
Why use rem?+
rem helps keep an interface consistent and accessible when users change their text size.