ASCII Code to Binary Converter

This converter works on code values, one at a time, from the table. Codes run from 0 to 127; anything above that is reported as out of range. For whole text rather than single codes, use Text to Binary; for a plain number, use Decimal to Binary.

Going the other way? Convert binary back to ASCII code →

How do you convert ASCII to binary?

ASCII Code to binary conversion takes one code value from the 0–127 table and writes that number in binary, padded to 8 digits so every code is the same width.

1. Read the code value. This example uses 65.
2. Convert the number to binary: 65 is 1000001.
3. Pad it on the left to 8 digits: 01000001.
4. Repeat for every code in the list and separate them with a single space: 65 = 01000001.

ASCII Code to Binary Conversion Table

The codes this page works through, each with the character it stands for and the same value in hex, octal and binary. Find the code in the first column and read across; the row is the whole conversion. Codes 0 to 31 and 127 have no glyph, so the Char column shows their short name instead. This page shows the rows you need; ASCII code chart (decimal, hex, octal, binary) carries all 128.

The base this page writes, defined by the digits it uses, how a value is marked, and what each position is worth.

Worked Example: 65 to Binary

One code value, taken from the table and written out in full. This is the same working the converter shows when you turn on "show steps".

Start with the code itself: 65. The table gives one row per code from 0 to 127, and that row is the whole answer — there is no arithmetic to get wrong, only a row to find. Reading the row across gives the same value in every base the table carries.

Writing 65 in binary gives 1000001, and the converter pads it on the left to 8 digits: 01000001. The padding is not decoration. It keeps every code the same width, so a run of codes can be split apart again later without a separator to guide it. A code typed in a different base lands on the same row, which is what the base selector is for.

Check it in reverse

The value looks the same read backwards. 01000001 maps to code 65, and code 65 maps to 65 — the table is a two-way lookup, not a calculation, so no rounding or padding can change the answer. To verify the result by hand, convert the binary bytes back to ASCII codes and compare it with the code you started from.

Worked examples: ASCII code to binary

Each example gives the value first, then the working. Click a value to load it in the converter.

Every example above reverses exactly — look the same bytes up as ASCII codes.

What Changes the Code Output?

Values above 127

A value above 127 is out of range and the converter says so rather than guessing. Codes 128–255 belong to extended sets such as Latin-1, not to ASCII, so there is no single right character for them. every ASCII code and its character lists every code that is in range.

Which base the code is written in

The same code can be typed as decimal, hex, octal or binary, and the base selector says which one you mean. 65, 41, 101 and 01000001 are all the letter A. Pick the wrong base and you look up a different row.

Control codes and printable codes

Codes 32 to 126 are printable characters; 0–31 and 127 are control codes. A control code has no glyph, so the table shows its short name instead — 10 is LF, 13 is CR. Converting one is valid; displaying one is not.

One code or a list

Several codes separated by spaces convert as a list, in order, and each keeps its own row. The separator is a display choice and does not change any value.

ASCII Code to Binary in Code

The same rule in one line. Both take code values and return their binary form.

Python: ' '.join(format(b, '08b') for b in s.encode('utf-8'))

JavaScript: [...new TextEncoder().encode(s)].map(b => b.toString(2).padStart(8, '0')).join(' ')

Common Mistakes

• Typing text where a code value belongs. The converter reads 72 as one code, not as the characters 7 and 2 — for whole text use write your name in binary (8 bits per character).
• Reading a code in the wrong base. 41 is A in hex and ) in decimal.
• Expecting a character above 127. That value is outside ASCII and the answer depends on which extended set is meant.
• Dropping the padding on a fixed-width code, so a list of codes can no longer be split apart.

Frequently Asked Questions

Related Conversions

• If your input is text rather than ASCII code, write your name in binary (8 bits per character) instead.
• If your input is binary rather than ASCII code, binary code to plain text instead.
• ASCII Code also converts to text by the same lookup — read ASCII codes 0-127 as characters.
• If your input is decimal rather than ASCII code, write a number in base 2 instead.
• If your input is hex rather than ASCII code, find the ASCII code behind a hex byte instead.
• If your input is text rather than ASCII code, find the ASCII code value of any letter instead.

The rest of the family sits on pick another conversion from the grid.