What this calculator does
A subscript generator turns ordinary text into the small, lowered characters used in chemical formulas like H2O, mathematical notation like a subscript index, and footnote markers. Rather than shrinking and shifting the text visually, it substitutes each character for a genuine Unicode subscript code point, so the result is real text that can be copied and pasted anywhere plain text is accepted, including places that do not support HTML formatting.
Unicode does not define a subscript version of every character. Digits, a handful of maths symbols and most lower-case letters have one, but capital letters and several lower-case letters (including b, c, d, f, g, q, w, y and z) simply were never assigned a subscript code point. Those characters are left unchanged in the output, and the calculator counts how many were affected so you know at a glance whether the conversion is complete or partial.
The formula
Each character typed is looked up against the fixed table of Unicode subscript code points. Digits 0 to 9, the +, −, = and bracket symbols, and most lower-case letters have a direct match and are substituted. Anything without a defined subscript equivalent, including every capital letter, is left exactly as typed.
| Term | Meaning |
|---|---|
| Subscript code point | A specific Unicode character that renders as a small, lowered version of the original, distinct from just styling text smaller with CSS. |
| Coverage gap | The set of characters, mostly capital letters and a handful of lower-case letters, that Unicode never assigned a subscript form for. |
The inputs explained
| Field | What to enter |
|---|---|
| Text | The text to convert. Works well for chemical formulas and short index labels; longer sentences will have more characters without a subscript match. |
When to use it
Writing chemical formulas in plain text
Chat apps, plain-text notes and many form fields do not support HTML subscript tags, so a genuine Unicode subscript character is the only way to write H2O or CO2 correctly outside of a word processor.
Footnote or index markers
A subscript number after a variable or term, such as an index in a sequence, reads clearly as a small trailing digit rather than needing brackets or extra punctuation to separate it from the main text.
Checking whether a piece of text will convert cleanly
Before using subscript text somewhere permanent, running it through the generator shows exactly which characters, if any, will not convert, since capital letters and a handful of lower-case ones are quietly left unchanged.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How different sample text converts to subscript
A few common uses, showing what converts and how many characters do not have a subscript form.
| Text entered | Subscript text | Characters without a true subscript form |
|---|---|---|
| H2O | H₂O | 2 |
| CO2 | CO₂ | 2 |
| x1 + x2 | ₓ₁ ₊ ₓ₂ | 0 |
| Sample Text | Sₐₘₚₗₑ Tₑₓₜ | 2 |
Questions
Why don't capital letters convert to subscript?
Unicode simply never assigned subscript code points for capital letters. This is a gap in the Unicode standard itself, not a limitation of this tool, and no combination of characters can work around it.
Will subscript text display correctly everywhere?
Almost everywhere, since these are standard Unicode characters rather than a special font or formatting. A very small number of very old systems or fonts may not render every subscript character, but modern devices and apps display them normally.
Is this the same as the superscript generator?
Same idea, different direction. The superscript generator raises characters for exponents and ordinals; this one lowers them, which is the convention for chemical formulas and indices.
Which lower-case letters are missing a subscript form?
B, c, d, f, g, q, w, y and z have no defined Unicode subscript equivalent. Every digit and most other lower-case letters do.
For the raised equivalent used in exponents and ordinal text, see the superscript generator.