# Bacon Cipher > Encode and decode the Bacon (Baconian) cipher, which writes each letter as five A/B symbols, with both alphabets and how to hide and find secret messages. - Page: https://linguaholic.com/tools/bacon-cipher/ - Type: free online tool (Converters & translators), no sign-up, runs in the browser - Publisher: Linguaholic (https://linguaholic.com/), made by Marcel Iseli - Last updated: October 3, 2026 - Open it pre-filled: https://linguaholic.com/tools/bacon-cipher/?text=hello - `text`: text to encode, or A/B (or 0/1) groups to decode; word gaps (two or more spaces or /) are kept (for example `hello`) - `mode`: direction: encode (default) or decode (for example `decode`) - `open`: open a section: steps (Bacon lookup table and worked letters), frequency (letter counts) or identify (which cipher is this?) (for example `steps`) ## What is the Bacon cipher? The **Bacon cipher**, also called the **Baconian cipher** or the biliteral cipher, writes every letter as a group of five symbols that come in only two kinds, usually shown as **A** and **B**. H, for example, is `AABBB`. The English philosopher and statesman Francis Bacon described it in 1605. What makes it special is not the code but where you can put it. Because any two kinds of thing can stand for A and B, a Bacon message can hide inside an ordinary sentence: in two typefaces, in capitals and small letters, in bold and plain text, even in a row of coins showing heads or tails. A reader who does not know to look sees only the sentence. Hiding the fact that a message exists at all is called **steganography**, and the Bacon cipher is its best-known example. ## How to use the Bacon cipher encoder and decoder 1. Choose **Encode** to turn text into A/B groups, or **Decode** to turn groups back into letters. 2. To decode, paste the groups. Zeros and ones work as well as A and B, and spaces between the groups are optional: the decoder reads the symbols five at a time. 3. Tap **Copy** to save the result. The lookup table in the tool shows which group became which letter. If your message is hidden in a sentence rather than written as A and B, first turn it into A/B: write A for every letter of one kind and B for every letter of the other (the section on solving below shows how). If you are holding a string of symbols and are not sure it is Bacon at all, the tool’s cipher helper can suggest which code it looks like. ## Frequently asked questions **What is the Bacon cipher?** The Bacon or Baconian cipher writes every letter as a group of five symbols of two kinds, usually A and B. H, for example, is AABBB. Because any two styles can stand for A and B, the code can be hidden inside ordinary text. **How do I decode a Baconian cipher?** Turn the message into A and B, split it into groups of five and look each group up in the Bacon alphabet. In the tool, choose Decode and paste the groups; 0 and 1 work as well as A and B. **What is the Baconian cipher key?** There is no secret key: the key is the Bacon alphabet itself, A = AAAAA, B = AAAAB and so on, which is the numbers 0 to 25 in five binary digits with A for 0 and B for 1. **What is the difference between the 24-letter and 26-letter Bacon alphabets?** Bacon's original 24-letter table gives I and J one code and U and V one code. The modern 26-letter table gives every letter its own code. The two agree up to I and then differ by one code, and by two after U. **How do you hide a message with the Bacon cipher?** Encode the secret, then write a cover sentence with five letters for every secret letter. Write each cover letter in one style for A and another for B, such as small letters and capitals, plain and bold, or two typefaces. **How do I solve a hidden Baconian cipher?** Look for something that comes in exactly two versions, write one as A and the other as B, and decode in groups of five. If you get nonsense, swap A and B; if it goes wrong only after I, try the 24-letter alphabet. **Who invented the Bacon cipher?** The English philosopher and statesman Francis Bacon. It is usually dated to 1605, when he wrote about ciphers in The Advancement of Learning, and he set out the full alphabet in De Augmentis Scientiarum in 1623. **Is the Bacon cipher binary?** Yes, in effect. Each letter is a five-bit binary number with A for 0 and B for 1, which gives 32 possible groups for 26 letters. Computer text uses eight bits per character instead. **Is this Bacon cipher tool free and private?** Yes. It runs entirely in your browser with no sign-up, and nothing you type is uploaded or stored. ## Data sources The code breaker's English letter frequencies and word checks come from Linguaholic’s English dictionary, built from the open ENABLE and SCOWL word lists. 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