Reference
Binary Code Alphabet
The binary code alphabet shows the 8-bit binary value for each letter. Capital A is 01000001 and capital Z is 01011010. Every character has a number in the ASCII standard, and binary simply writes that number in base 2.
Uppercase and lowercase are different
Uppercase and lowercase letters have different binary values because they are different characters in ASCII. Capital A is 01000001 (65) while lowercase a is 01100001 (97). The difference is always exactly 32, which flips a single bit.
That single-bit difference between cases is a neat quirk of the ASCII design and a favourite fact in beginner computing lessons.
Frequently asked questions
What is A in binary?
Capital A is 01000001, which is the number 65 written as an 8-bit binary byte. Lowercase a is 01100001, or 97.
Why do uppercase and lowercase letters differ in binary?
They are separate characters in ASCII with different numbers. Uppercase and lowercase of the same letter always differ by 32, which changes just one bit.