CSS Unit Converter

Developer Tools

Convert between CSS units like px, rem, em, vh, and vw instantly. Free online CSS unit conversion tool for responsive web design.

100% Client-Side. Your data never leaves your device.
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How to use CSS Unit Converter

  1. 1Enter your input in the text area above
  2. 2Click the action button to process your data
  3. 3View the result and copy it to your clipboard

Common Use Cases

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Quick Processing

Process your data quickly and efficiently.

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Secure & Private

All processing happens in your browser.

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Free to Use

This tool is completely free with no signup.

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Mobile Friendly

Works on any device with a browser.

Frequently Asked Questions

What is the difference between px, rem, and em?

px is an absolute unit (fixed pixels). rem is relative to the root element's font-size (usually 16px). em is relative to the parent element's font-size. Using rem is recommended for consistent sizing across your site since it always references the root font-size.

When should I use rem vs em?

Use rem for global spacing, font sizes, and layout dimensions where you want consistency. Use em for component-level sizing that should scale with the parent's font size, like padding inside a button. rem prevents compounding issues that em can cause in nested elements.

What are vh and vw units?

vh (viewport height) and vw (viewport width) are relative to the browser viewport. 1vh = 1% of viewport height, 1vw = 1% of viewport width. They're useful for full-screen sections, responsive typography, and elements that need to scale with the window size.

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