Decimal, binary, hex & ASCII numbers conversion table (2024)

This is a conversion table with decimal numbers next to their binary and hex equivalents. The matching ASCII characters are listed as well, with more elaborate descriptions of some characters on this page. If none of these words mean anything to you, jump to the bottom of this page for more information on:

• binary numbers
• hex or hexadecimal numbers
• ASCII

ASCII codes 0 to 127

Extended ASCII codes

Below are the extended ASCII codes for character codes 128 to 255. This table uses the ISO 8859-1 or ISO Latin-1 encoding. Codes 128-159 contain the Microsoft Windows Latin-1 extended characters. Other variations exist but this is the most commonly used set of character codes.

Binary numbers

A computer number system that consists of 2 numerals, 0 and 1. It is sometimes called base-2.
Since computers do not have 10 fingers, all the counting within the computer itself is done using only 2 numerals: 0 and 1 (or “on” and “off” or “false” and “true”).

Hexadecimal numbers

The hexadecimal system (hex for short) uses numbers from 0 to 15. It starts off like the decimal system: 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9 but then comes A which equals 10 and then B, C, D, E, and F (which of course equals 15). The next number is 10 which is actually 16 in decimal and so on….
Because it can be impossible to distinguish between a hex and a decimal number (is that ’25’ a decimal 25 or is it 25 in hex which equals 37 decimal?) it is customary to put a lowercase ‘h’ after each hex number. So 25 is a decimal number and 25h is a hex one.

ASCII

ASCII stands for American Standard Code for Information Interchange. It is a standard that was defined in 1963to allow computers to exchange information, regardless of the manufacturer.

• Since computers basically work numbers based, the ASCII character set consists of 128 decimal numbers, ranging from 0 through 127, assigned to letters, numbers, punctuation marks, and the most common special characters. Since a computer needs 7 bits to represent the numbers 0 to 127, these codes are sometimes referred to as 7-bit ASCII.
  • Numbers 0 to 31 are used for control codes – special instructions such as indicating that the computer should make a sound (ASCII code 7) or the printer should start from a new sheet of paper (ASCII code 12).
  • ASCII codes 32 to 47 are used for special characters, starting with the space character.
  • After the numbers 0 to 9 (ASCII codes 48 to 57), you once again get some special characters, from the colon to the @ symbol.
  • The letters start with the capital A from ASCII code 65 onwards. The lowercase a to z characters take up ASCII codes 97 to 122. You may wonder why the lowercase characters don’t simply follow their capital brethren. Remember: this is ASCII, this is computer stuff from the dark ages. If you take a capital U, which is ASCII code 85, and add 32 to that code, you get character code 117, which is the lowercase u. 32 is the magic ‘distance’ between any upper and lower case character and 32 is a truly magical, efficient number that any computer or nerd can relate to. Even I love 32.
  • Codes 123 to 127 are once again special characters, including the tilde (~).
• All computer systems also use numbers 128 through 255 to represent additional characters, but this list is not really universally standardized. That is why the above table is split up into two parts. The first table with the 7-bit ASCII codes is universal across all computers. The second extended ASCII table is not – it is what current Windows machines use.
• Because 256 characters are not sufficient to represent all characters used in Asian languages and to solve the annoying compatibility problems with different codes being used for codes 128 to 255, a new standard has emerged. The Unicode character set contains more than 32000 characters.