CSS Units Converter
Convert between px, rem, em, pt, pc, in, cm, and mm for web typography and layout. Set your base font size and every unit recalculates accurately.
Step-by-step guide to the CSS Units Converter
- Set the root font size, 16px by default, since rem depends on it.
- Enter a value in any unit field.
- All equivalent values update instantly in the other units.
- Copy the conversion you need into your CSS.
Practical scenarios for the CSS Units Converter
- Converting a px-based design mockup into accessible rem-based CSS.
- Checking em equivalents for component-scoped sizing.
- Translating print-style point measurements into web units.
- Scaling typography correctly for responsive layouts.
How the CSS Units Converter works under the hood
Conversions anchor on the CSS reference pixel and the standard relationships: one inch equals 96px, one point equals 4/3 px, one pica equals 12 points, and rem values derive from the root font size you set, defaulting to 16px. Because responsive best practice sizes text in rem while mockups arrive in px, this conversion is a daily bridge between design and code. The math runs locally as you type.
What the CSS Units Converter does not do
em values depend on the parent element's font size in your real document, so the converter's em figures assume a single nesting level from the base.
Common questions about the CSS Units Converter
Why size text in rem instead of px?
rem respects the user's chosen browser font size, keeping layouts accessible to people who scale text.
What is the default root font size?
16px in every major browser, which you can adjust here if your project sets its own base.
How many pixels is one point?
One point is 4/3 of a pixel, so 12pt equals 16px.
Last reviewed: October 2026.