Cryptogram Solver

How to solve a cryptogram

1. Paste your cipher text into the text area above.
2. Each unique cipher letter appears in the substitution table below the text.
3. Type your guesses for each cipher letter — the decoded text updates instantly as you type.
4. Single-letter words are almost always A or I — start there.
5. Two-letter words are commonly: OF, TO, IN, IS, IT, BE, AS, AT, SO, HE, BY, OR, DO.
6. The most frequent letters in English text are E, T, A, O, I, N, S, H, R in that order.

What is a cryptogram?

A cryptogram is a short piece of encrypted text where each letter has been substituted with a different letter — this is called a simple substitution cipher (or Caesar cipher when each letter is shifted by a fixed amount). The substitution is consistent throughout the message: if A encodes to X in one place, it encodes to X everywhere. The challenge is to figure out the substitution mapping using letter frequency, word patterns, and context clues.

Frequency analysis

The most powerful technique for cracking substitution ciphers is frequency analysis. In English text, the letter E is the most common (about 13% of all letters), followed by T (~9%), A (~8%), O (~8%), and I (~7%). The cipher letter that appears most often in your message is very likely to be E. Similarly, common two-letter pairs (digraphs) include TH, HE, IN, ER, AN, and RE — spotting these in the cipher can confirm multiple substitutions at once.

Word pattern hints

• Three-letter words starting with a known letter narrow down candidates quickly.
• Repeated letter patterns (e.g. ABBA like THAT or NOON) are easy to spot and confirm.
• Apostrophes indicate contractions — the pattern X'X is likely T'S, and X'XX is likely I'VE or I'LL.
• The word THE is the most common three-letter word — if you spot a repeated three-letter word, try T, H, E for those cipher letters first.