Stop dividing by 16 in your head.
Type a value in any of the four CSS length units and the other three fill in instantly —
rem and em resolve against the base font size, and 100%
always equals the base in pixels. Change the base to 10 for the classic 62.5% trick, or to
whatever your design system actually uses.
Every result row has its own copy button, and the whole converter runs offline as pure
arithmetic. Bookmark ?base=10&from=rem to pin your team's setup and only ever
touch the input.
⚙️ Settings & Customization
- Theme
- Size
- Transparent background
- Language
- 🎨 Accent color
Changes apply live — the embed link on the right and the preview above update instantly.
📖 How to embed in Notion
- Copy the embed link from the sidebar on the right.
- Open the Notion page you want the widget on and type
/embed. - Paste the link into the embed dialog and press
Embed link. - Drag the embed's bottom edge to resize it to taste.
🆕 What's new in v1.0
- ✦ Live four-way conversion as you type — px, rem, em, %
- ✦ Configurable base font (16px default, any value via URL)
- ✦ Per-row tap-to-copy results
- ✦ Arabic-Indic numerals in Arabic mode
- ✦ 100% offline — pure arithmetic, no API
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