CSS Unit Converter

Convert a single length value between nine CSS units systems: px, rem, em, vw, vh, pt, cm, mm, and in. Conversions go through pixels as the common base, using the configurable root font size for rem/em and a configurable viewport size for vw/vh. All eight other units are shown at once in the result grid.

1. Enter the value to convert in the numeric input. 2. Choose the source unit from the dropdown next to it. 3. Set Root Font Size (used for rem and em; default 16px). 4. Set Viewport width and height (used for vw and vh; default 1920x1080). 5. Read the equivalent values for every other unit in the result grid.

Everything is converted to px first, then to the target unit. px is identity. rem and em both multiply/divide by the root font size (em here uses the same root, not a parent font size). vw and vh use (value/100) * viewport dimension. pt uses 96/72, cm uses 96/2.54, mm uses 96/25.4, in uses 96 — all per the CSS spec at 96 CSS pixels per inch. Results use up to 6 decimal places, with 0 shown for extremely small values.