Cryptogram rules

What is a cryptogram?

A cryptogram takes a piece of text — usually a famous quote — and encodes it with a substitution cipher. Every A might become R, every B might become W, and so on. The substitution is consistent: if A=R in one place, A=R everywhere in the puzzle. Spaces and punctuation stay the same.

Your job is to figure out the mapping and decode the original quote. Substitution ciphers go back to ancient Rome — Julius Caesar used a simple shift cipher for military messages. Modern cryptograms are solved the same way: pattern recognition and frequency analysis.

The rules

1. Each letter in the original text has been replaced by exactly one other letter.
2. The mapping is one-to-one: no two different letters map to the same encoded letter.
3. Spaces, punctuation, and capitalization are preserved from the original text.
4. Click an encoded letter and type the letter you think it represents. The mapping applies everywhere that encoded letter appears.
5. The puzzle is solved when every letter is correctly decoded and the original quote is revealed.

How to solve a cryptogram

1. Single-letter words. In English, these are almost always "I" or "a." Assign one and see if it makes sense elsewhere in the puzzle.
2. Apostrophes. If you see X'Y, the 'Y is likely 't (can't, don't, won't, isn't) or 's. This gives you T or S immediately.
3. Three-letter words. "THE" is the most common three-letter word in English. If you see the same three-letter pattern repeated, try THE. You get three letters at once.
4. Frequency analysis. Count how often each encoded letter appears. The most frequent is likely E, T, A, or O. The least frequent is probably Z, Q, X, or J.
5. Double letters. Common doubles are LL, SS, EE, OO, TT, FF, PP. Rare doubles include AA, II, UU. If you see a double, test the common ones first.
6. Build on confirmed letters. Each correct letter opens up surrounding words. A partially-decoded word like _O_E might be COME, DONE, GONE, HOME, etc. Use context to pick the right one.

English letter frequencies

This table shows how often each letter appears in typical English text. Use it to map the most frequent ciphertext letters to likely plaintext letters.

Tips

• Start at the edges of the quote where short words cluster. Prepositions, articles, and pronouns are easy to identify by length and position.
• Use the frequency analysis tool on this site. It shows a live bar chart of encoded letter frequencies — compare it to the standard English frequencies above.
• If a guess creates an impossible combination elsewhere (ZZ or QQ in the middle of a word), backtrack and try a different mapping.
• Common word endings: -ING, -TION, -ED, -LY, -ER, -EST. Spotting these gives you multiple letters at once.

Frequently asked questions

Related puzzle rules

• Word Search rules — Find hidden words in a letter grid
• Crossword rules — Fill entries from clue-based definitions
• Anagram rules — Rearrange letters to form words