CSS Unit Converter
Convert between px, em, rem, pt, pc, %, vw, vh. Tweak the root and viewport context to match your design system.
Value to convert
Context (assumed defaults)
About this tool
A CSS unit converter for designers and front-end developers. Enter any value in any unit and instantly see equivalents in seven others. The context panel lets you set custom root font size, viewport dimensions, and percentage base — exactly matching your project setup.
How to use it
Quick steps to get the most out of this utility.
- 1
Enter a value
Type the number and select its current unit.
- 2
Optionally adjust the context
Default 16px root and your current viewport are used unless you change them.
- 3
Read off the conversions
All 8 units are calculated live. The active unit is highlighted.
- 4
Copy and paste into CSS
Each card has a copy button that includes the unit suffix.
Quick reference
px, pt (point = 1/72 inch), pc (pica = 12pt). Fixed regardless of parent or viewport.
em (parent font size), rem (root font size). Most useful for typography and accessible scaling.
vw (1% viewport width), vh (1% height). Great for hero sections and fluid sizing.
% is relative to the parent property — width to parent width, font-size to parent font-size, etc.
Frequently asked questions
What does 1rem equal in pixels?+
By default, 1rem = 16px because that's the browser's default root font size. If you set html { font-size: 18px } in CSS, then 1rem becomes 18px. The whole point of rem is that this scales site-wide if you change the root.
When should I use rem vs em?+
Use rem for font sizes, spacing, and layout — predictable because it's always relative to the root. Use em for component-internal scaling — e.g. padding inside a button that should grow with the button's font size.
What's the difference between vw and %?+
1vw = 1% of the viewport width, regardless of any parent. 1% in width is 1% of the parent element's width. Use vw for hero text or full-bleed elements; use % for elements that should respect a container.
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