ASCII to Hex Converter
Convert ASCII text to hex byte strings.
2 bytes
48 69
Need the other direction? Hex to ASCII Converter →
This tool converts ASCII text to hex bytes instantly: type Hi and you get 48 69. The output is spaced, uppercase and two digits per byte — the format serial terminals, protocol testers and CRC calculators expect. A live byte counter shows exactly how many bytes you are about to send.
How it works
Every ASCII character has a numeric code: H is 72 decimal, 0x48 hex; i is 105, i.e. 0x69. The converter writes each character's code as a two-digit hex byte in order. Control characters typed into the box (like a newline, 0x0A) convert the same way, which is useful when a device protocol requires an explicit CR/LF terminator.
Worked example
hex : 48 69
ascii: OK⏎ (with newline)
hex : 4F 4B 0A
Parameters
| Parameter | Value | Notes |
|---|---|---|
| Input | ASCII text | one byte per character |
| Output | spaced uppercase hex | e.g. 48 69 |
| Control chars | converted literally | newline → 0A |
| Non-ASCII | low byte kept | single-byte workflow |
Python implementation
# ASCII text -> spaced uppercase hex bytes
def ascii_to_hex(text: str) -> str:
return " ".join(f"{ord(c) & 0xFF:02X}" for c in text)
assert ascii_to_hex("Hi") == "48 69"FAQ
▸What format is the hex output?
Uppercase two-digit bytes separated by spaces, e.g. Hi becomes 48 69. That format pastes cleanly into most serial terminals, protocol test tools and this site's other calculators.
▸How are line breaks and special characters handled?
Every character in the input becomes exactly one byte of its ASCII code — a line break in the text box becomes 0A (LF). The byte counter under the input shows how many bytes the output contains.
▸What about non-ASCII characters like é or 한?
The converter keeps only the low byte of each character code, since it targets single-byte ASCII workflows. For multi-byte UTF-8 encoding use a dedicated Unicode tool.
▸Can I convert hex back to text?
Yes — the companion Hex to ASCII page, linked below the tool, does the reverse.
▸Is my text uploaded?
No. Conversion runs entirely in your browser.