Chemical formulas need subscript numbers to be readable — H2O isn't wrong exactly, but H₂O is standard notation. Word processors have equation tools for this, but for chat, notes, spreadsheets, or anywhere a full equation editor is overkill, copy-paste Unicode subscript digits do the job in one paste using the subscript generator.
Why subscript numbers work perfectly (unlike subscript letters)
Unicode defines a complete set of subscript digits, 0 through 9, in the Superscripts and Subscripts block. That's different from subscript letters, where only a handful exist — see subscript vs superscript for the full picture. Because formulas are almost entirely digits with a few letters (H, O, C, N and so on), and those letters stay as regular capitals since Unicode doesn't define subscript capital letters, the result still reads clearly: H₂O, CO₂, C₆H₁₂O₆, NH₃.
Step by step
1. Open the subscript generator and type the numbers you need — just the digits, like 2 or 6.
2. Copy the subscript digit result.
3. Type your formula normally (H, O, C, etc. as regular capital letters), then paste the subscript digit in place of the regular number.
4. Repeat for each number in the formula, since the tool converts what you currently have typed, not a whole pre-written formula at once.
Where this is safe to use
Copy-paste subscript works anywhere that accepts plain Unicode text — lab notebooks kept digitally, chat with classmates, slide decks, spreadsheets, and social captions. It is not the same as a real equation object in Word or LaTeX, so if your formula needs to be machine-readable by scientific software (searchable, editable as a structured formula), use your editor's built-in subscript or equation tool instead — the Unicode version is a visual stand-in, not structured chemistry data.