CSS Unit Converter
Convert pixel values to rem and em units for scalable CSS design. Set your html font-size (default 16px) and instantly see the equivalent in every relative unit, with copy-ready values.
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Enter a value and unit, set the document root font size, and the converter computes the equivalents. Px values convert to rem (relative to root) and em (relative to parent).
Convert
Root (and parent) font sizepx1em = 1rem = 16px at this base
- Pixels
16px - Em (parent)
1em - Rem (root)
1rem - Points
12pt
Frequently asked questions
What is the difference between rem and em?
rem is relative to the root (html) font size; em is relative to the current element's font size. This tool converts against both.
Does the root font size matter?
Yes. With a 16px root, 1rem = 16px. Browsers that honor user font-size preferences change this, which is why rem enables accessible scaling.
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