Reference
The Bacon Cipher Explained
The Bacon cipher, invented by Sir Francis Bacon, represents each letter as a unique sequence of five A's and B's. Its real trick was never the letters themselves; Bacon designed it to be hidden inside ordinary text using two subtly different typefaces, making the true message invisible to anyone not looking for it.
Last updated 14 July 2026
A five-symbol code for every letter
Each letter of the alphabet is given a unique combination of five A's and B's, the same idea as writing its position in the alphabet as a five-digit binary number. Five symbols allow for 32 combinations, more than enough for 26 letters.
Bacon's original 1605 table only needed 24 codes, since I shared a code with J and U shared one with V. This translator gives every letter from A to Z its own distinct code, so encoding and decoding never lose information.
Hiding the code in plain sight
In Bacon's method, the A's and B's were never written out directly. Instead, two visually similar typefaces stood in for A and B within an entirely different, innocent-looking cover text, so the secret message was disguised as ordinary writing.
This translator shows the A/B code directly rather than hiding it in typefaces, which makes it useful for puzzles, learning the idea, and seeing how letters become five-bit binary values, the same principle used inside every computer today.
Frequently asked questions
Is the Bacon cipher the same as binary code?
The underlying idea is identical: each letter becomes a five-digit binary number, just written as A and B instead of 0 and 1. Binary code for computers uses eight digits per character rather than five.
Why did Francis Bacon design it this way?
He wanted a cipher that did not look like a cipher at all. By hiding the A/B pattern inside two similar typefaces, a secret message could be smuggled inside completely ordinary-looking text.