CONVERTER · MATH · NUMBER SYSTEMS
Every letter you type is a number underneath, and hex is how programmers write those numbers. At the default, “Hi” becomes 48 69 — H is 72 (0x48), i is 105 (0x69), each written as one two-digit byte. Flip the direction to paste hex back and decode it, in spaces, 0x-prefixed, or continuous form.
Text mode turns each character into its two-digit hex byte: H is 0x48, i is 0x69. Hex mode reads byte pairs back into characters and accepts space-separated bytes, 0x-prefixed bytes, or one continuous string. Programmers read hex instead of binary because one hex digit covers exactly four bits, so a byte is two short digits instead of eight long ones.
Setup: text “Hi”, direction text to hex, space-separated style.
Line 1 — look up each character. H is ASCII code 72; i is code 105.
Line 2 — convert to hexadecimal. 72 in base 16 is 48 (4 × 16 + 8); 105 is 69 (6 × 16 + 9). Each byte becomes exactly two hex digits.
Line 3 — join with spaces. The result is 48 69 — 2 bytes for a 2-character word. With the 0x style it reads 0x48 0x69; continuous, 4869.
Line 4 — check the round trip. Switch direction, paste 48 69 back, and the converter returns “Hi”. A hex string with an odd number of digits, a non-hex character, or a non-ASCII character in text mode is reported as an error instead of silently producing wrong output.
Binary for “Hi” is 01001000 01101001 — 16 digits to read. Hex for “Hi” is 48 69 — 4 digits for the same 2 bytes, because each hex digit stands for exactly 4 bits. That is why memory dumps, color codes, hashes, and network packets are all shown in hex: it is binary, compressed to a quarter of the length, with no information lost. One byte is always two hex digits, which is also why an odd-length hex string can never be valid — a byte cannot be half a digit.
| Character | Decimal code | Hex byte | Note |
|---|---|---|---|
| H | 72 | 48 | First byte of the default example. |
| i | 105 | 69 | Second byte of the default example. |
| A | 65 | 41 | Uppercase letters run 65–90 (41–5A hex). |
| a | 97 | 61 | Lowercase letters run 97–122 (61–7A hex); exactly 32 above uppercase. |
| 0 | 48 | 30 | Digits run 48–57 (30–39 hex). Note: the character “0” is not the value zero. |
| (space) | 32 | 20 | The space character itself is a byte, not a separator here. |
| ! | 33 | 21 | Punctuation lives in the 33–47 and 58–64 ranges. |
| ~ | 126 | 7E | The last printable ASCII character. |
| Output | Formula | What it means |
|---|---|---|
| Hex for a character | ASCII code in base 16, two digits, uppercase | H (72) → 48; padding keeps every byte two digits. |
| Hex for a word | one byte per character, joined per the chosen style | “Hello” → 48 65 6C 6C 6F — 5 bytes, 10 hex digits. |
| Text from hex | each byte pair back to its ASCII code | 69 → 105 → i. |
| Byte count | hex digits ÷ 2 | 48 69 is 4 hex digits = 2 bytes. An odd digit count is an error, not a guess. |
This converter covers printable ASCII only (codes 32–126). It does not handle accented letters, emoji, or other Unicode characters — those need UTF-8, where a character can occupy multiple bytes, and they are reported as errors here rather than silently mangled. Control characters (codes 0–31) and delete (127) are likewise excluded. Hex input must use only 0–9 and A–F (either case), in complete byte pairs; an odd-length string, a non-hex character, or an empty input is reported as an error with the problem named.
Bright Side Kit. "ASCII to Hex Converter: Text to Hexadecimal Code Tool." https://brightoolbox.com/ascii-to-hex/ Accessed October 24, 2026.Data sources48 69. H is ASCII code 72, which is 48 in hexadecimal; i is code 105, which is 69. Each character becomes exactly one byte, two hex digits.
48 65 6C 6C 6F. H = 48, e = 65, l = 6C, l = 6C, o = 6F — five bytes, ten hex digits. Notice the double l appears twice, as it should.
61. Lowercase a is ASCII code 97, which is 61 in hex. Uppercase A is 65, or 41 in hex — exactly 32 lower, which is why case differs by one hex digit in the high nibble.
Yes — switch the direction to Hex → Text. Paste space-separated bytes (48 69), 0x-prefixed bytes (0x48 0x69), or one continuous string (4869). All three decode to “Hi”.
Because a byte is two hex digits. A string like “486” has three digits, so the last byte is half missing. The converter reports it instead of inventing a digit, which would silently change the decoded text.
Same bytes, different notation. Binary writes each byte as 8 bits (Hi = 01001000 01101001); hex writes it as 2 digits (Hi = 48 69). Hex is shorter and is what programmers, debuggers, and color pickers actually display.
Because they are not ASCII. This tool covers printable ASCII only (codes 32–126). Accented letters and emoji live in Unicode and need UTF-8 encoding, where one character can take several bytes. Converting them as if they were ASCII would produce wrong output, so the converter says so instead.
No. 6c and 6C decode to the same byte, and 4869, 48 69, and 0x48 0x69 all decode to “Hi”. Output is uppercase by convention; input accepts either case.