🔤 Binary to ASCII Converter with Steps
By Shihab Mia · Updated 2026-07-18
Whitespace and commas are ignored. Groups must be 8 bits each, or one long string whose length is a multiple of 8.
| # | Binary (8 bits) | Decimal | Hex | Character |
|---|
This binary to ASCII converter turns 8-bit binary groups back into readable text in one step, so 01001000 01101001 decodes to "Hi". Paste your bits with spaces or commas between each byte, or as one long unbroken string, and the tool splits them into 8-bit groups, reads each group as a number, and maps it to its ASCII character. It also shows a per-byte table with the decimal code, hex value, and character so you can check every step.
What is the Binary to ASCII Converter?
ASCII (American Standard Code for Information Interchange) is a character encoding that gives every letter, digit, and common symbol a number from 0 to 127. The uppercase letter H is 72, the lowercase i is 105, a space is 32, and the digit 0 is 48. Computers store these numbers in binary, base 2, and a single ASCII character fits neatly into 8 bits (one byte). That is why binary text is almost always written in groups of eight 0s and 1s: each group is one character.
Converting binary to ASCII reverses that storage step. You take each 8-bit group, read it as a base 2 number, and look up the character with that code point. For 01001000 the place values that hold a 1 are 64 and 8, so 64 + 8 = 72, which is the letter H. For 01101001 the 1 bits sit over 64, 32, 8, and 1, giving 64 + 32 + 8 + 1 = 105, which is the letter i. Put them together and 01001000 01101001 spells "Hi". The converter above does exactly this for every group you enter.
Grouping matters. When the bits are separated by spaces or commas, each token is treated as one byte and must be exactly 8 bits long. When you paste one continuous string with no separators, the tool slices it into 8-bit chunks from the left, so the total length has to be a multiple of 8. If a group is the wrong size or the text contains anything other than 0, 1, and separators, the tool shows a friendly error instead of guessing, because a shifted or truncated byte would decode to the wrong character.
Strictly speaking, ASCII only defines codes 0 to 127. Bytes from 128 to 255 belong to extended sets like Latin-1, and modern text often uses UTF-8, where some characters span several bytes. This tool decodes each 8-bit group to its Unicode code point using String.fromCodePoint, so plain ASCII text always comes out correct, and single-byte extended values still resolve to a character. For multi-byte UTF-8 you would decode the raw bytes with a UTF-8 decoder, but for the everyday job of turning binary code back into letters and words, byte-by-byte ASCII decoding is exactly what you want.
When to use it
- Decoding a binary message from a puzzle, CTF challenge, or homework question back into plain text.
- Reading a byte stream captured from a file, serial port, or network packet as human-readable characters.
- Teaching or learning how characters are stored, with a live table showing each byte, its code, and its letter.
- Sanity checking the output of a text to binary encoder by converting the bits back and confirming they match.
How to use the Binary to ASCII Converter
- Paste your binary into the box, either as 8-bit groups separated by spaces or commas, or as one long string.
- Read the decoded text at the top; it updates instantly as you type or when you tap an example.
- Scan the per-byte table to see how each 8-bit group maps to a decimal code, a hex value, and a character.
- Press Copy to grab the decoded text, and fix any group the tool flags if the bit count is off.
Formula & method
Worked examples
Decode 01001000 01101001 into text.
- Split on the space into two 8-bit groups: 01001000 and 01101001.
- Read the first group as base 2: the 1 bits are over 64 and 8, so 64 + 8 = 72.
- Code 72 in ASCII is the uppercase letter H.
- Read the second group: 1 bits over 64, 32, 8, and 1 give 64 + 32 + 8 + 1 = 105, which is the letter i.
Result: 01001000 01101001 decodes to "Hi".
Decode the unspaced string 0100000101000010 into text.
- There are no separators, so check the length: 16 bits, which is a multiple of 8.
- Slice from the left into two bytes: 01000001 and 01000010.
- First byte: 1 bits over 64 and 1, so 64 + 1 = 65, which is the letter A.
- Second byte: 1 bits over 64 and 2, so 64 + 2 = 66, which is the letter B.
Result: 0100000101000010 decodes to "AB".
Common ASCII characters with their decimal, hex, and 8-bit binary codes
| Character | Decimal | Hex | Binary (8-bit) |
|---|---|---|---|
| space | 32 | 20 | 00100000 |
| 0 | 48 | 30 | 00110000 |
| 9 | 57 | 39 | 00111001 |
| A | 65 | 41 | 01000001 |
| H | 72 | 48 | 01001000 |
| Z | 90 | 5A | 01011010 |
| a | 97 | 61 | 01100001 |
| i | 105 | 69 | 01101001 |
| z | 122 | 7A | 01111010 |
Bit place values inside a single 8-bit byte
| Bit position (from right) | Power of 2 | Place value |
|---|---|---|
| 0 | 2 to the 0 | 1 |
| 1 | 2 to the 1 | 2 |
| 2 | 2 to the 2 | 4 |
| 3 | 2 to the 3 | 8 |
| 4 | 2 to the 4 | 16 |
| 5 | 2 to the 5 | 32 |
| 6 | 2 to the 6 | 64 |
| 7 | 2 to the 7 | 128 |
Common mistakes to avoid
- Groups that are not exactly 8 bits. Each ASCII character is one byte, so every separated group must be 8 bits. A group of 7 or 9 bits shifts every following character. If you separate bytes with spaces, keep each group at exactly eight 0s and 1s.
- An unspaced string whose length is not a multiple of 8. When there are no separators the bits are sliced into 8-bit chunks from the left. If the total is not divisible by 8, the last chunk is incomplete and the text is wrong. Count your bits, or add spaces between bytes.
- Mixing up 7-bit and 8-bit encodings. Classic ASCII only needs 7 bits (codes 0 to 127), but binary text is written in 8-bit bytes with a leading 0. Do not drop the leading zero; 1001000 is only 7 bits and will not line up as a byte.
- Expecting emoji or accented letters from single bytes. Characters beyond code 127, including emoji and many accented letters, use multi-byte UTF-8, not one 8-bit ASCII byte. Decoding those byte by byte gives the wrong result; use a UTF-8 decoder for full Unicode text.
Glossary
- ASCII
- A character encoding that maps letters, digits, and symbols to numbers from 0 to 127, the basis for how text is stored as binary.
- Binary
- A base 2 number system using only 0 and 1. Each ASCII character is stored as an 8-bit binary number.
- Byte
- A group of 8 bits. One byte holds values 0 to 255 and, in ASCII text, represents a single character.
- Bit
- A single binary digit, either 0 or 1. Eight bits make one byte.
- Code point
- The numeric value assigned to a character. For plain ASCII the code point equals the byte value, for example 72 for H.
- UTF-8
- A modern Unicode encoding where common ASCII characters stay one byte but other characters use two to four bytes.
Frequently asked questions
How do you convert binary to ASCII?
Split the binary into 8-bit groups, read each group as a base 2 number, and map that number to its ASCII character. For example 01001000 is 72, which is the letter H, so 01001000 01101001 becomes "Hi".
What is 01001000 01101001 in ASCII?
It decodes to "Hi". The group 01001000 is 72 (the letter H) and 01101001 is 105 (the letter i).
Why does my binary have to be in groups of 8?
Each ASCII character is stored in one 8-bit byte. Splitting the bits into groups of 8 lines up each byte with one character, so a length that is not a multiple of 8 means a byte is incomplete and the text will be wrong.
Can I paste binary without spaces?
Yes. If there are no spaces or commas the tool slices the string into 8-bit chunks from the left, as long as the total number of bits is a multiple of 8.
Does this tool handle spaces and punctuation?
Yes. A space is ASCII code 32 (00100000) and punctuation has its own codes too, so any byte you enter decodes to its correct character, including spaces, digits, and symbols.
Why does an accented letter or emoji not decode correctly?
Characters above code 127, including emoji and many accented letters, use multi-byte UTF-8 rather than a single 8-bit ASCII byte. This byte-by-byte converter decodes plain ASCII correctly; full Unicode text needs a UTF-8 decoder.