How to Type a Plus-Minus Sign
The plus-minus sign (±) indicates a range or tolerance in measurements, engineering specifications, and mathematical expressions. Essential for precision and uncertainty notation.
Quick Reference
Windows
Hold Alt and type 0177 on the numeric keypad.
Alt + 0177
Mac
Press Option + Shift + =.
Option + Shift + =
Linux
Press Ctrl + Shift + U, type 00B1, press Enter.
Ctrl + Shift + U, 00B1, Enter
HTML
Use the HTML entity ± or numeric ±.
± or ±
Common Uses
The plus-minus symbol is widely used across scientific, engineering, and mathematical contexts to express variation, uncertainty, or dual solutions.
- Engineering tolerances: 100mm ±0.5mm (acceptable range: 99.5mm to 100.5mm)
- Scientific measurements: 25.3°C ±0.2°C (measurement uncertainty)
- Mathematics: x = ±5 (x equals positive or negative 5)
- Statistics: Mean ± standard deviation (68.2 ± 3.4)
- Manufacturing specs: Dimensions with acceptable variance
- Quadratic equations: Solutions using ± in the quadratic formula
Interpretation
The plus-minus sign has two main interpretations depending on context:
1. Range or tolerance: When used with a single value (e.g., 50 ±5), it means the actual value falls between 45 and 55. The ± indicates acceptable deviation from the nominal value.
2. Dual solutions: In mathematics, x = ±3 means x can be either +3 or -3. Both values are valid solutions to the equation.
Technical Details
Unicode: U+00B1
HTML Entity: ±
HTML Decimal: ±
Alt Code (Windows): Alt + 0177
Name: PLUS-MINUS SIGN