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Computer Science · Encoding

ASCII & Unicode Lookup

Look up the code point of any character — and the character behind any code.

Direction
Each character is shown with its Unicode code point.
First character
A

Decimal 65 · U+0041 · 01000001

CharDecimalHexBinary
A65U+004101000001

The uppercase letter “A” is ASCII and Unicode code point 65, which is 0x41 in hexadecimal and 01000001 in binary. Lowercase “a” is 97 (0x61). Every character maps to a number — its code point — and ASCII covers the first 128 of these, all shared by Unicode.

What a code point is

A code point is the number a character set assigns to a character. In ASCII the printable and control characters run from 0 to 127, so 7 bits is enough to hold any of them. Unicode extends this idea to every writing system on Earth, numbering more than a million possible code points — but its first 128 are exactly ASCII, unchanged. Writing the number in different bases (decimal, hex, binary) does not change the character; it is the same value shown three ways.

Common characters and their codes

The same code point in decimal and hexadecimal.

CharacterDecimalHex
A650x41
a970x61
0 (digit zero)480x30
(space)320x20
(newline, \n)100x0A

Worked example: finding the code for “A”

Look up “A” and read off the three representations of code point 65.

  1. 1
    Switch to Text → codes. This mode reads each character and reports its code point.
  2. 2
    Type the character. Enter A. The tool calls codePointAt to get its number: 65.
  3. 3
    Read the decimal value. A = 65. That is the everyday ASCII number for the capital letter.
  4. 4
    Read hex and binary. 65 in hexadecimal is 0x41 (U+0041); in 8-bit binary it is 01000001.
  5. 5
    Check the lowercase offset. Lowercase a is 97. Since 97 − 65 = 32, the same offset turns any uppercase letter into its lowercase form.

ASCII, Unicode, and UTF-8

ASCII is the original 128-character set, occupying code points 0–127; those 128 values are the very start of Unicode, so any ASCII text is already valid Unicode. UTF-8 is the encoding that stores those code points as bytes: code points 0–127 take a single byte identical to plain ASCII, while higher code points use two to four bytes. The case difference is a tidy 32 — “A” (65) plus 32 is “a” (97), and the same holds for every letter, which is why bit 5 alone flips letter case in ASCII.

What is the difference between ASCII and Unicode?
ASCII defines 128 characters numbered 0–127. Unicode is a far larger standard covering every writing system, but its first 128 code points are identical to ASCII, so plain ASCII text is also valid Unicode.
What exactly is a code point?
A code point is the integer a character set assigns to a character — for example 65 for “A”. It is just a number; the character only appears when something renders that number with a font.
Why is “A” equal to 65?
The ASCII committee placed the uppercase letters starting at 65 (0x41), so A is 65, B is 66, and so on through Z at 90. Unicode kept those same assignments.
Why is lowercase 32 higher than uppercase?
Lowercase letters were placed exactly 32 code points after their uppercase counterparts: a is 97, which is 65 + 32. That single bit difference makes converting case a fast bitwise operation.
When should I use hex instead of decimal codes?
Hex is preferred when code points need to line up with bytes — one byte is two hex digits — which is why Unicode is written as U+0041 rather than 65. Decimal is friendlier for quick reading.
How are non-ASCII characters like é or emoji numbered?
They sit above 127 in Unicode — é is U+00E9 (233) and many emoji are above U+1F000. The tool reads them with proper code-point iteration, so each is shown as one row.