ASCII to Binary Converter

ASCII — the American Standard Code for Information Interchange — was published by the American Standards Association in 1963 and later written up as RFC 20. It was designed for teletype machines: electromechanical typewriters chatting over phone lines. Seven bits gave 128 values, enough for every English letter in both cases, the digits, punctuation, and a set of machine-control codes; the eighth bit on those lines was reserved for error checking (parity). That is why ASCII stops at 127 — and why every ASCII character still fits neatly in one modern byte.

Printable ASCII: the full 95-character table

Values 32–126 are the printable characters — everything you can actually see, from the space to the tilde. The letters also live on our binary alphabet page with a search box; here is the complete printable set including digits and punctuation.

The invisible half: control characters

Values 0–31 and 127 are control characters — teletype commands that do things instead of printing. Three you still meet daily: 00001001 (9) is Tab, 00001010 (10) is Line Feed, 00001101 (13) is Carriage Return — Windows line endings are still CR followed by LF, a direct teletype inheritance. One honest limit when using the converter: control bytes decode correctly in ASCII mode, but they are invisible in the output, so a perfectly correct result can look empty or oddly spaced.

ASCII and UTF-8: same bytes for English

UTF-8 was deliberately designed so its first 128 code points are exactly ASCII — that backward compatibility is a big reason it won. When you convert plain English with the text to binary converter, you are looking at ASCII values carried inside UTF-8. On this page, ASCII mode is a strict subset: ideal for homework and classic tables, but switch to UTF-8 the moment your text includes é, 你 or an emoji — the article what is UTF-8 explains how multi-byte encoding works.

Common mistakes

• Mistake: expecting ASCII to cover é or 你. Correction: those characters do not exist below 128 — switch the encoding to UTF-8 instead of forcing an error.
• Mistake: confusing a digit character with its number. The character “7” is ASCII 55 (00110111), not the number 7 (00000111). Correction: digits as text use character codes, just like letters do.
• Mistake: forgetting the space. Correction: a space is ASCII 32 (00100000), a full byte like any letter — “I love you” is ten bytes, not eight.

Practice

1. What is the ASCII decimal code for “A”? 65 — binary 01000001. Every uppercase letter follows in order: B is 66, C is 67.

2. Decode 01110011 as ASCII. 64 + 32 + 16 + 2 + 1 = 115 — the lowercase letter s. Check it in the converter above.