ASCII 177
Plus-Minus Sign (±)
Latin-1 Supplement
Plus-minus sign (±). Used to express margins of error and tolerance ranges (5 ± 0.5).
Common uses & context
Decimal 177 (0xB1) is Plus-Minus Sign, part of the Latin-1 Supplement (128–255). Plus-minus sign (±). Used to express margins of error and tolerance ranges (5 ± 0.5). It renders as '±' and its binary byte is 10110001.
This is where single-byte ASCII ends and encoding matters. In Latin-1 (ISO-8859-1) '±' is the single byte 0xB1. In UTF-8 — today's default for the web — the same character is the multi-byte sequence 0xC2 0xB1. Treating a Latin-1 byte as UTF-8 (or vice versa) is the usual reason accented letters and symbols turn into mojibake like é or €. The Unicode code point is U+00B1, and in HTML you can write it as ± or ±.
All encodings at a glance
| Decimal | 177 |
| Hexadecimal | 0xB1 |
| Octal | 0261 |
| Binary | 10110001 |
| HTML numeric entity | ± |
| HTML named entity | ± |
| URL encoding | %B1 |
| UTF-8 bytes | 0xC2 0xB1 |
Code snippets
JavaScript
String.fromCharCode(177); // "±"
177.toString(16); // "b1"Python
chr(177) # control char ±
ord(chr(177)) # 177
hex(177) # '0xb1'HTML
± <!-- named entity -->
± <!-- numeric entity -->Programming notes
- ▸Single byte 0xB1 in Latin-1, but the multi-byte sequence 0xC2 0xB1 in UTF-8 — never assume one byte per character above code 127.
- ▸Unicode code point U+00B1; HTML entity ±.
- ▸If '±' shows as mojibake, the encoding declared and the encoding used disagree — align both on UTF-8.
Unicode & UTF-8 note
In Unicode this is U+00B1. In UTF-8 it encodes to the byte sequence 0xC2 0xB1. In legacy Latin-1 (ISO-8859-1) it is a single byte 0xB1, which is why Latin-1 files often appear as mojibake when interpreted as UTF-8.
Frequently asked questions
What character is ASCII code 177?
ASCII code 177 is the character '±' (Plus-Minus Sign). In hexadecimal it is 0xB1, in octal 0261, and in binary 10110001.
What is 0xB1 in ASCII?
Hexadecimal 0xB1 equals decimal 177, which is the character '±' (Plus-Minus Sign). To convert hex to ASCII yourself, read the two hex digits as a base-16 number (0xB1 = 177) and look up that code point.
How do I write the character with code 177 in code?
In JavaScript use String.fromCharCode(177); in Python use chr(177); in HTML use the numeric entity ± or the named entity ±. In a URL it is percent-encoded as %B1, and in UTF-8 it is stored as the byte sequence 0xC2 0xB1.
Is '±' part of standard ASCII?
No. Standard ASCII covers codes 0–127 only. '±' is code 177, part of the Latin-1 Supplement (128–255, sometimes called "extended ASCII"). It is a single byte 0xB1 in Latin-1 but a multi-byte sequence (0xC2 0xB1) in UTF-8.