What ± means
Use both signs, not just “approximately.” The plus/minus notation in x = a ± b gives two answers: a + b and a − b.
What it means when someone sends it to you
3 readingsA reported measurement
Uncertainty around the measured value.
An algebraic solution
Evaluate using each sign.
A quoted specification
Permitted deviation from the target.
Don't confuse it with
1Combination ideas
3Measurement example: 10 with uncertainty of 2.
Algebra example: a + b or a − b.
Opposite sign choices, kept paired.
Questions people ask
1Why does ± show as a box on some devices?
Because that device's fonts have no glyph for it. The character is still correct and still copies correctly — the box is a missing glyph, not a broken character.
How to type ±
Windows (Word)
Alt+XType 00B1, then Alt+X to get ±.
Windows
Win+Rrun charmap for the full table, or use the emoji picker's Ω symbols tab (Win + .).
macOS
Control+Command+SpaceOpen the character viewer and search “plus-minus sign”.
Linux
Ctrl+Shift+UType 00b1, then Enter or Space.
HTML
±CSS
\00B1Type plus minus in Word
As of 2026, type \pm inside an equation, then press Space.
Codes and encoding1 code points
HTML decimal
±
HTML hex
±
CSS content
content: "\00B1";
Each escape is closed by the next backslash; a trailing space is needed before a literal hex digit.
URL encoded
%C2%B1
1
On screen
1
Code points
1
JS .length
2
UTF-8 bytes
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.