Text to ASCII

In 1963 a standards committee had to settle something oddly specific: what single number should represent the letter A, everywhere, on every machine. They picked 65. That decision is ASCII, and it is still the foundation everything from a keyboard press to a text file rests on.

A seven-bit standard built for teleprinters

ASCII — the American Standard Code for Information Interchange — assigns every letter, digit, punctuation mark and control signal a number from 0 to 127, fitting into just seven bits. That is 128 possible values, enough for the full English alphabet in both cases, the ten digits, common punctuation, and a set of control codes inherited from teleprinter equipment.

Those control codes still matter more than people realise: code 10 is a line feed, code 13 is a carriage return, and code 9 is a tab. Every time a text file breaks a line, it is using a code assigned in that original 1963 standard.

Upper and lower case are exactly 32 apart

A is 65. Lowercase a is 97. The difference, 32, is not a coincidence — it is exactly one binary bit, the value 32 being 2 to the fifth power. Every letter pair works the same way: B is 66 and b is 98, Z is 90 and z is 122.

That fixed gap is why converting case in code is often just a matter of flipping one bit rather than looking up a whole new character, a shortcut built directly into the numbering rather than bolted on afterward.

ASCII codes worth knowing by heart

What ASCII cannot do

• Represent accented letters — é, ñ, ü and the rest — since none of them fit in the original 128 codes.
• Represent non-Latin scripts such as Cyrillic, Arabic, Chinese or Japanese in any form.
• Represent emoji, which did not exist yet and would need thousands of codes ASCII was never designed to hold.
• Distinguish itself from Unicode’s UTF-8 for the first 128 characters — they are identical there, which is exactly where ASCII’s limits start to matter for anything else.

Text to ASCII questions