± Plus-Minus Sign: Meaning, Uses, and Shortcuts

The ± (plus-minus) sign is a mathematical symbol used to indicate a choice of exactly two possible values, usually representing a positive and a negative. In everyday language and science, it most commonly represents a margin of error, an approximation, or a tolerance range, such as "100 ± 5" meaning anywhere from 95 to 105.

The origins of the plus-minus sign date back to the early 1600s. French mathematician Albert Girard first used a variation of the symbol, but English mathematician William Oughtred popularized the modern ± look in his 1631 work Clavis Mathematicae. Since then, it has become a staple in mathematics, physics, and engineering to express quadratic equations and precise scientific measurements.

You will spot the ± symbol everywhere from high school algebra textbooks to casual internet conversations. In mathematics, it famously appears in the quadratic formula. In science and engineering, it defines the bounds of accuracy, telling you exactly how much wiggle room exists in a measurement. On social media and messaging apps, users casually drop the ± symbol to mean "give or take" or "more or less" when estimating time, money, or party attendees.

In the Unicode standard, the plus-minus sign is designated as U+00B1 and lives in the Latin-1 Supplement block. Because it was included in early computing standards, almost every modern font, browser, and operating system supports it flawlessly without rendering issues. In programming, developers often use it in comments or output strings to denote thresholds and variance.

Typing the ± symbol is straightforward once you know the shortcuts. On a Mac, simply press Option + Shift + =. On a Windows PC, hold down the Alt key and type 0177 or 241 on your numeric keypad. If you are texting on an iPhone or Android device, tap into the numeric and symbol keyboard, then long-press the plus (+) or equals (=) key to reveal the ± option as a pop-up. When in doubt, you can always copy and paste it straight from the web.

The ± sign shares a close relationship with its inverted cousin, the ∓ (minus-plus) sign. Mathematicians use the minus-plus symbol when equations require opposite operations in a specific linked order. Naturally, it also builds upon the standard + (plus) and - (minus) characters. While simple in design, the plus-minus sign packs a massive amount of data into a single character, making it the ultimate shorthand for everyday approximations.