CSS Unit Converter

CSS supports multiple units for sizing elements, fonts, and spacing. Pixels (px) are absolute units, while rem and em are relative to font size — making them essential for responsive design. This tool converts between all common CSS units instantly, with an adjustable base font size for accurate rem/em calculations.

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How to Use

Select your source unit from the buttons at the top, then enter a numeric value. All conversions are shown instantly. Adjust the base font size (default 16px) if your project uses a different root font size. Click the copy icon next to any result to copy it.

Common Use Cases

• •Converting pixel values to rem for responsive typography
• •Translating print units (pt, cm, mm) to screen units (px)
• •Calculating em values relative to a custom base font size
• •Generating consistent spacing values across different unit systems
• •Converting design specs from inches or points to pixels