ROT13 Cipher
ROT13 encoder and decoder, plus any Caesar shift from 1 to 25: each letter A to Z moves that many places. Digits, punctuation and accents stay as typed. How it works
Use the ROT13 Cipher
13 is ROT13. Other numbers give a Caesar cipher.
ROT13 (shift 13) is its own inverse; applying it twice restores the original text. Any other shift is undone by choosing Decode with the same shift. It shifts only the 26 unaccented English letters (A-Z, a-z); accented and non-Latin letters, digits and punctuation pass through unchanged. It hides text from a casual glance and is not encryption: there is no key.
About the ROT13 Cipher
ROT13 replaces each letter A to Z with the letter 13 places further on, wrapping from Z to A: A becomes N and N becomes A. Because 13 is half of 26, the same step encodes and decodes, so Uryyb, Jbeyq turns back into Hello, World. Digits, punctuation and accented letters are left as they are.
The ROT13 alphabet
| Letter | Becomes | Letter | Becomes |
|---|---|---|---|
| A | N | N | A |
| B | O | O | B |
| C | P | P | C |
| D | Q | Q | D |
| E | R | R | E |
| F | S | S | F |
| G | T | T | G |
| H | U | U | H |
| I | V | V | I |
| J | W | W | J |
| K | X | X | K |
| L | Y | Y | L |
| M | Z | Z | M |
Lower case follows the same pairs: a becomes n, n becomes a.
ROT13 examples
| Text | ROT13 |
|---|---|
| Why did the chicken cross the road? | Jul qvq gur puvpxra pebff gur ebnq? |
| Gb trg gb gur bgure fvqr. | To get to the other side. |
| Hello, World | Uryyb, Jbeyq |
| ROT13 | EBG13 |
| café 123 | pnsé 123 |
| Привет | Привет |
Frequently asked questions
- How do I decode ROT13?
- Paste the encoded text into the same box with Places at 13, the default. Decoding is the same 13-place shift as encoding, so Gb trg gb gur bgure fvqr. comes out as To get to the other side.
- Is ROT13 encryption?
- No. It is an encoding with no key: anyone who knows the rule, or pastes the text here, can read it. It keeps a spoiler or an answer from being read at a glance and protects nothing.
- Is ROT13 a Caesar cipher?
- Yes, a Caesar shift of 13. It is the only shift that undoes itself in the 26-letter alphabet. Set Places to any number from 1 to 25 for another Caesar shift, with Encode or Decode: at 3, Hello, World becomes Khoor, Zruog. The tool has no ROT5 or ROT47 for digits and symbols.
- How do I decode a Caesar cipher when I do not know the shift?
- Choose Decode and try the places one at a time until the output reads as words; there are only 25 shifts. Yhql, ylgl, ylfl decodes at 3 to Veni, vidi, vici. A shift of 13 is ROT13, where Encode and Decode give the same result.
- What happens to numbers and accented letters in ROT13?
- They stay as typed. Only the 26 unaccented letters move, so "Zoë, 42 años" becomes "Mbë, 42 nñbf": the ë and ñ, the digits and the comma are untouched, and Cyrillic text such as Привет comes out the same.
- How much text can it convert?
- Up to 200,000 characters; the box stops there and the page says so. Convert longer text in parts.
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