About Uppercase
Uppercase converts a block of text to capital letters using the standard Unicode case mapping built into the browser. It is most often reached for to make a heading, a label or a shout, and because the conversion runs on the whole block at once it is a reliable way to normalise text before comparing it with something that is expected to be upper case.
The mapping is the language-neutral default rather than a locale-specific one. That distinction shows up in a few languages where the capital form of a character depends on the language being used; without locale tailoring you get the general mapping, which is the right answer for identifiers and code and can look wrong in Turkish-language prose.
One consequence of case mapping surprises people: for a small number of characters the upper-case form is longer than the lower-case one, so uppercasing can change the number of characters in the string. If you are uppercasing text to fit a fixed-width field, measure the result afterwards rather than assuming the length is unchanged.
This is a one-way transformation applied in a single step, which rules out a few things you might reasonably expect. There is no option to target particular words or passages — the setting applies to everything pasted in. There is no way to preview a character-by-character comparison against the original, and no mode that leaves already-uppercase text alone. Nor does the page offer a small-capitals or sentence-case variant; each of those is a different mapping rather than a setting on this one. The previous version of your text is not retained, so copy anything you may want back before replacing it.
How to use Uppercase
- 1 Paste the text you want in capitals.
- 2 Read the converted output, which is copied in place.
- 3 Re-measure the length if the text is going into a field with a fixed size.
Frequently asked questions
Can uppercasing change the number of characters?
Yes, for a small set of characters whose capital form is longer than the lower-case one. The classic example is the German sharp s, which maps to a capital form of two characters. Copy the output rather than assuming the length is unchanged.
Is there any risk of data being altered beyond the casing?
No — only case mapping is applied, so digits, punctuation, spaces and line breaks pass through untouched. That makes the conversion safe to apply to a block of structured text such as a list or a table, where only the letters change.
Why do accented letters get converted correctly?
Because the mapping is Unicode-aware rather than ASCII-only. Accented letters, Greek and Cyrillic all have defined case pairs and convert accordingly, which was the main reason to prefer a Unicode mapping over the old ASCII-only approach.
Free, online, and private
Free to use
Uppercase is completely free. There is no account to create, no login, and no hidden charge or usage limit.
Runs online in your browser
It is a free online tool that runs entirely in your browser. Nothing to download or install — open the page and start using it right away.
Your data stays private
All processing happens locally on your device. Your input is never uploaded, stored, or tracked, so it never leaves your browser.
How Uppercase behaves in detail
These are the specifics of this implementation — the exact ranges, defaults and fixed settings you are working with.
| Parameter | Value |
|---|---|
| Operation | JavaScript toUpperCase() applied to the whole string in a single pass |
| Locale | no locale argument — the default Unicode mappings are used, so a Turkish i becomes I and not the dotless form |
| Non-letters | untouched — digits, punctuation, symbols and whitespace pass through as they are |
| Expanding characters | the German ß becomes SS and the ff ligature becomes FF, so the output can be longer than the input |
| Update mode | live — recomputed on every keystroke |
Compiled from the implementation of this tool and checked against it by itoolnet.
What Uppercase does not do
Knowing the edges of a tool saves more time than another list of its features. These are the cases where it will not do what you might expect.
- The conversion is one-way and destroys the original casing. There is no paired lowercase pass over the same buffer, no diff and no history, so a string that has been through this tool can only be restored by retyping it or pasting the original again.
- Some characters grow when they are uppercased. ß becomes the two letters SS and the ligature ff becomes FF, so a string measured against a character budget can overflow merely by being converted — the count has to be checked after the conversion, not before.
- Locale-specific rules are not applied and cannot be requested. Without a locale argument the dotless-i rule for Turkish and Azeri text is unavailable, so capitalising that text here produces a technically correct uppercase string that a native reader will consider wrong.
Tested and documented by itoolnet, the team that builds and maintains this site.