CSS Unit Converter
px, rem, em, pt, %, vw, vh — with live viewport.
16 px
1 rem
1 em
12 pt
100 %
1.563 vw
2.083 vhvw/vh use the live viewport size; % and em use the base font sizes you set above.
About the CSS Unit Converter
Convert a CSS value between px, rem, em, pt, percent, vw and vh in one table. The root and parent font sizes are configurable for accurate rem and em math, and vw/vh use your live viewport dimensions, which update as you resize the window — exactly how those units behave in the browser.
How to use the CSS Unit Converter
- Enter a value and pick its unit from the dropdown.
- Set the Base font size (rem) and Parent font size (em) to match your CSS.
- Read the full conversion table listing all seven units.
- Resize the browser window to watch vw and vh values track the live viewport.
CSS Unit Converter FAQ
Why do rem and em need separate base sizes?
rem is relative to the document root font size while em is relative to the parent element, so the tool keeps both configurable and defaults each to 16px.
How is pt calculated?
CSS defines 1pt as 1/72 of an inch and the reference pixel as 96dpi, so 1pt equals 96/72 = 1.333px, and the conversion uses exactly that ratio.
Are vw and vh based on my actual window?
Yes — the viewport stat shows your current inner width and height and listens for resizes, so the vw/vh columns reflect reality on your screen right now.