Code Breaking: What is a Caesar Cipher?

A cipher is a method of creating a hidden message by transforming each letter into another letter. Julius Caesar popularized the Caesar Cipher, one of the oldest known methods of encryption.

A form of shift cipher, initially used as a means of encrypting written communications between forces in the field. To form an encrypted message, letters in a plain text message by a set number of spaces, creating an enciphered text.

Someone who may stumble across an encrypted message may have trouble understanding what it means, however, if someone knew the shift value used for the encrypted message the message can be easily decoded.


Say we wanted to encrypt the message “COME AT ONCE” with a shift value of “2”

Each letter in the message is shifted two spaces ahead, where an A becomes a C, and a B becomes D, etc.

You can see how a Caesar Cipher works with the interactive wheel below by clicking on the wheel. (note. The interactive wheel displays best on a desktop screen).

Make your own Caesar Cipher guide


  • Scissors
  • Paper
  • A printer
  • A paperclip
  • A button

You can download a template below and have a go at making your own Caesar Cipher wheel!