About Minus-or-plus Sign
Minus-or-plus Sign is the Unicode character ∓ at codepoint U+2213 in the Mathematical Operators block of the Basic Multilingual Plane (BMP).
Reference
The sign that always takes the opposite of whatever plus-minus is doing in the same expression. General category Sm, in Mathematical Operators since Unicode 1.1, and it shares its partner's two unusual properties: bidirectional class ET, the class of characters that attach to numbers, and line break class PR, so it stays bound to what follows. Unicode's mathematical classification files it as class V — unary or binary by context — the same as its twin. It has three HTML names, ∓, ∓ and ∓, and no Windows-1252 slot. Its code chart entry cross-references exactly one character, and it is the twin.
Typical uses
- Paired trigonometric identities, where the signs on the two sides must correspond in reverse
- Any expression folding a sum and a difference into one line
- Nothing at all on its own — it has no meaning without its partner
At a glance
- U+2213, Mathematical Operators; Unicode 1.1; general category Sm
- Bidi class ET; line break class PR; East Asian Width Narrow
- HTML: ∓, ∓ or ∓. No Windows-1252 slot
- One cross-reference only, to plus-minus sign
Historical Notes
Origins
Unicode 1.1, 1993, in the original Mathematical Operators block — a block away from its partner, which came in from Latin-1 Supplement with a Windows-1252 byte behind it. That split is the reason one of the pair is easy to type and the other is not.
One cross-reference, and what it implies
This one carries a single reference, to plus-minus. Nothing else in Unicode resembles it, and nothing else relates to it. For a character whose meaning is defined entirely by correspondence with another, a code chart entry consisting of one pointer is unusually apt.
Vary, like its twin
MathClass-15 files both signs as class V — unary or binary depending on context — while filing multiplication sign, division sign and division slash as class B, binary only.
Developer Notes
| Unicode Codepoint | |
| Decimal | |
| UTF-8 (hex) | |
| UTF-16 (hex) | |
| HEX Entity | |
| HTML Entity | |
| CSS (\xxxx) | |
| JavaScript | |
| Python |
How to Use Minus-or-plus Sign
To use the Minus-or-plus Sign symbol (∓) in HTML, insert the
entity ∓ directly into your markup. The decimal entity ∓ works in any HTML-serialised document.
In CSS pseudo-elements use content: '\2213';.
In JavaScript and TypeScript the escape '\u2213' evaluates to ∓. In Python source, write '\u2213'.
The character encodes to E2 88 93 as UTF-8 bytes and 2213 as UTF-16 code units. Its decimal codepoint is 8723.
This is a text-based Unicode character. It will render in the current font on most platforms. If a font lacks this glyph, the browser may show a placeholder or fall back to a system font.
Things to know
- No Windows-1252 slot, which is most of why it is rarer than its twin. Plus-minus has byte 0xB1 and this one has nothing.
- Three HTML names resolve to it: ∓, ∓ and ∓. `∓` and `∓` also work.
- Line break class PR, so a renderer keeps it attached to the following number, exactly as with its twin.
- East Asian Width Narrow, so unlike its twin it will not change cell width in a terminal.
- No mainstream keyboard layout produces it. Where a document needs it, it generally arrives through a typesetting system rather than by being typed.
- Pattern_Syntax applies; identifier grammars following Unicode's rules reject it.
Comparisons
In the Wild
An encyclopaedia article on standard deviation carries three plus-minus signs, six multiplication signs and two dot operators — a page entirely willing to reach for the correct character — and no occurrence of this one at all. Paired identities are a narrower need than intervals and tolerances, and that page reflects it.
The honest limit is worth stating: mathematics textbooks, physics courses and typeset papers are where this sign genuinely lives, and none of those is a web page a reader can be pointed at. General web prose is what can be read, and there it is absent.
Pages change; this is what those showed on the day.
FAQ
What does it mean on its own?
Nothing. It has no value of its own; it takes the opposite sign to whatever plus-minus is doing elsewhere in the same expression.
Why does Unicode cross-reference only one character?
Because only one is related to it. For a character defined by correspondence, a single pointer is the whole entry.
Why is it rarer than ±?
Partly need, partly encoding: its twin has a Windows-1252 byte and this character has none, so it could not be typed through the era that fixed which symbols people use.
How do I type it?
No mainstream layout offers it. Use ∓, `∓`, or your typesetting system's own spelling.
Does it break lines differently?
No — like its twin it is line break class PR, so it stays attached to the number that follows.