ASCII Values for Letters and Characters Explained

ASCII (American Standard Code for Information Interchange) is the numeric system computers use internally to represent text characters — a very different scale from the simple A1Z26 alphabet cipher.

How ASCII differs from A1Z26

While A1Z26 starts counting at 1 for A, ASCII assigns uppercase A the value 65 and lowercase a the value 97 — because ASCII covers punctuation, digits, and control characters too, not just the 26 letters.

Uppercase letter values

Uppercase letters run from 65 (A) through 90 (Z) in consecutive order, so each letter’s ASCII value is exactly 64 higher than its A1Z26 position. See the A1Z26 conversion guide for a refresher on that base method.

Lowercase letter values

Lowercase letters run from 97 (a) through 122 (z) — 32 higher than the matching uppercase letter, a detail programmers rely on constantly when converting text case in code.

Why ASCII is case-sensitive

Unlike A1Z26, where “Hello” and “HELLO” convert identically, ASCII mode treats uppercase and lowercase letters as different values, since computers distinguish between the two. See the A1Z26 vs A0Z25 comparison for how those two systems handle case instead.

Try it yourself

Switch the main converter to ASCII mode to see the real character codes your browser and computer use behind the scenes, or check the full alphabet reference chart. For puzzle ideas using ASCII values, see how alphabet numbers work in puzzles.