This tool converts a length between every CSS unit at once — px, rem, em, pt, pc, in, cm, mm and Q — so you can switch between absolute and relative units without doing the maths by hand. It is useful when translating a design’s physical measurements into pixels, or converting pixel values into responsive rem units.
How it works
The absolute units are anchored to the CSS rule that 1 inch = 96px. Everything is expressed relative to a pixel and converted through px:
| Unit | Pixels |
|---|---|
| px | 1 |
| in | 96 |
| pc (pica) | 16 |
| pt (point) | 96/72 ≈ 1.333 |
| cm | 96/2.54 ≈ 37.795 |
| mm | 96/25.4 ≈ 3.7795 |
| Q | 1mm ÷ 4 ≈ 0.9449 |
The relative units depend on font size: rem uses the root font size and em uses the parent font size, both defaulting to 16px and editable to match your CSS.
Example
Enter 16px:
16px = 1rem (at 16px root) = 12pt = 1pc = 0.1667in = 0.4233cm
So 16 pixels equals exactly 1rem at the default root size, or 12 points. All conversions run entirely in your browser — nothing you enter is sent to a server.
Enter a value, pick its unit, and read the equivalent in every other unit instantly. Everything runs in your browser; nothing is uploaded.