Letter Frequency Counter

English letter frequency

Across ordinary English prose the order is fairly stable: E is far ahead of everything else at around 12% of all letters, then T, A, O, I and N clustered between 6% and 9%. At the other end, J, Q, X and Z together account for well under 1%.

That stability is what makes frequency analysis work. It is also why short samples mislead — a single sentence can put H or W at the top by accident, and the profile only becomes trustworthy over a few hundred letters.

Breaking a substitution cipher

The classic method, in the order it actually works:

• Paste the ciphertext here and find its commonest letter. It is probably E.
• Single-letter words are A or I. Two-letter words are dominated by OF, TO, IN, IT, IS, BE, AS, AT, SO, WE, HE.
• The commonest three-letter word by a long way is THE. Finding it usually gives you three letters at once.
• Doubled letters are most often LL, EE, SS, OO or TT.
• Once you have a few letters, use the pattern solver on the partly-decoded words — it takes exactly the "some letters known, some blank" input a half-solved cryptogram gives you.

Checking a pangram

A pangram uses every letter at least once. Paste one here and any letter with a count of zero is the one you missed — faster and more reliable than reading the alphabet under your breath.