What this calculator does
A Caesar cipher is one of the oldest known encryption methods: each letter in a message is shifted a fixed number of positions through the alphabet. This tool lets you build a short word letter by letter and see it encoded.
How the calculation works
Each selected letter’s position in the alphabet is shifted forward by the chosen amount, wrapping back to ‘A’ after ‘Z’ (using modular arithmetic on a 26-letter alphabet). Uppercase and lowercase letters are shifted independently, and spaces are left unchanged.
Because the shift amount is the only ‘key’, a Caesar cipher is easy to break with modern tools and is used here for educational and recreational purposes only, not for securing sensitive information.
Last reviewed August 2026