Pick a category and type a value in any unit — every unit updates live with per-row copy, using exact conversion factors (an inch is exactly 25.4 mm) and localized formatting. A swap-friendly favorite pair sits on top; the data category explains decimal vs binary prefixes.
Privacy ledger
Data acquired
None.
Libraries used
Lit 3 — bundled into the tool file itself.
Data stored
None.
Data transmitted
None.
Use it on your own page
Download the tool as a single self-contained HTML file: readable source with the Lit library included, zero network requests — it works opened straight from your disk, and you can customize everything.