Classroom code breaker

ASCII
Decoder Lab

Turn numbers into text. Turn text into code. Use the board, test your message, then decode the pattern hiding underneath the letters.

Converter Console

Live decoding. Type and the answer updates immediately.

Encode Text

text → code

Type a word or sentence.

Output appears here.

Decode Decimal

65 → A

Separate numbers with spaces or commas.

Output appears here.

Decode Binary

01000001 → A

Use 8 bit binary groups.

Output appears here.

ASCII Board

Dense on purpose. Scan it like a cipher sheet. Click a decimal, hex, or character cell to copy it.

control symbol number letter
Printable characters start at decimal 32. Decimal 0 to 31 are control codes, which usually do not print visible letters.

How the code works

What is ASCII?

ASCII is a character code. It gives common keyboard characters a number so computers can store and share text.

  • The letter A is stored as decimal 65.
  • The letter a is stored as decimal 97.
  • A space is stored as decimal 32.
A word is really a list of character codes. For example, HI becomes 72 73.
What is binary?

Binary is a number system that uses only two digits: 0 and 1. Computers use binary because digital circuits are built around two states: off and on.

  • Decimal is base 10 because it uses ten digits: 0 through 9.
  • Binary is base 2 because it uses two digits: 0 and 1.
  • ASCII numbers are often written as 8 bit binary groups.
Decimal 65 becomes binary 01000001, which represents the character A.