Atbash Cipher

How to use the Atbash Cipher

1. 1Enter your text.
2. 2Pick the units or options from the menus if the Atbash cipher tool offers them.
3. 3Read the Atbash cipher in the large result box.
4. 4Look at the extra rows for related figures.
5. 5Press Copy result to keep the answer.

When you need the Atbash cipher

People use it for puzzles, escape rooms, geocaching clues and classroom lessons about codes. It also appears in the history of Hebrew texts, where it was used with that alphabet.

Because there is no key, Atbash gives no real security and can be broken at a glance. It is a fun and gentle introduction to substitution ciphers.

How the Atbash cipher is worked out

Letter number n (A = 0) becomes letter number 25 − n. So A↔Z, B↔Y, C↔X, and the middle pairs M↔N. Hello, World becomes Svool, Dliow. Applying the cipher to Svool, Dliow gives back Hello, World.

Every answer on this page comes from that one rule, so you can check any result by hand with a calculator. The figures shown underneath, such as other units, are conversions of the same answer.

• Encodes and decodes
• Keeps case and punctuation
• Instant results

Mistakes to avoid with Atbash cipher

This tool handles the 26 letters of the English alphabet. Accented letters and non-Latin scripts pass through unchanged.

On phone and computer

On a phone, type into the boxes one after another and read the Atbash cipher underneath; Copy result puts it on the clipboard for a message or a note. On a computer the inputs sit on the left and the answer on the right, so you can change one figure and watch the Atbash cipher move. The atbash cipher works the same on both.

Checking your Atbash cipher by hand

A good habit is to test the atbash cipher with a case you already know. Hello, World becomes Svool, Dliow. Applying the cipher to Svool, Dliow gives back Hello, World.

If your own figures give a surprising answer, repeat the working yourself: Letter number n (A = 0) becomes letter number 25 − n. So A↔Z, B↔Y, C↔X, and the middle pairs M↔N. Small differences usually come from rounding, from mixing units, or from a typing slip in one of the inputs. Atbash is a simple swap of the alphabet, so it makes a fun first puzzle. If you want a code with a shift instead, ROT13 and Caesar Cipher is the classic next step. Vigenère Cipher adds a keyword for a harder result, and Rail Fence Cipher scrambles letters by position rather than by swapping them.

Features

• No key means no security
• English letters only
• Great for puzzles
• Clear messages when the Atbash cipher inputs make no sense
• Copy the result with one tap
• Private: nothing is uploaded

Frequently asked questions