CSS Unit Converter

Convert px and rem both ways.

Runs locallyNo signupMobile readyCopyableFree

📐CSS Unit Converter

All processing happens locally

Value

From

Root size (px)

Viewport (px)

Viewport height

Parent font size (px, for em)

Result

CSS Unit Converter is a tool for responsive CSS units, processing runs locally in your browser, so your input never reaches a server.

Results update as you change values; copy or download when ready.

Paste or type your content into the input field at the top, or press the sample button to load demo data.
Adjust the options below the input, such as output format, separators, letter case or precision.
Press the main button to run the conversion. Results appear instantly in the output panel without a page reload.
When the result looks right, use the copy button in the corner, or download it as a local file.

Clean up stray spaces and line breaks before pasting for more accurate results.

Why prefer rem for responsive layouts?+

rem scales with the root font size, so the whole UI grows when users increase browser text size. em depends on the parent and compounds quickly.

Which width is used for vw?+

vw is one percent of the viewport width. The default here assumes a 1920px design; change it to match yours.

Is CSS Unit Converter free to use?+

Yes. The tool is completely free with no usage limits, and you never need an account or a sign-in.

Is the text I enter uploaded anywhere?+

No. All processing runs locally in your browser, so the input never reaches a server and is never logged or stored.

Does CSS Unit Converter work on a phone or tablet?+

Yes. The layout is mobile-first, so inputs and buttons stay comfortable on phones and tablets in both orientations.

Can I copy the result into my own document?+

Yes. A copy button in the output panel puts the result on your clipboard, and you can also download it as a text file.