Plus-Minus Sign ±

The Plus-Minus Sign character (±) is a standard HTML entity defined in the HTML specification. In HTML source code, it can be written using the named entity reference ±, the decimal numeric character reference ±, or the hexadecimal numeric reference ±. The character is assigned Unicode code point U+00B1 in the Universal Character Set.

The plus-minus sign indicates that a value can be either positive or negative, or that a measurement has a margin of error. It combines the plus and minus signs into a single character and is widely used in mathematics, science, engineering, and statistics for expressing tolerances, uncertainties, and dual solutions.

Mathematical HTML entities enable web authors to display proper mathematical notation without relying on images or specialized rendering libraries like MathJax or KaTeX. While complex equations and multi-line formulas may still benefit from dedicated math typesetting tools, individual symbols expressed as HTML entities render quickly, remain accessible to screen readers, and can be styled with CSS just like regular text content.

When deciding how to encode the Plus-Minus Sign character in your HTML documents, the named entity ± is generally the most readable choice for developers reviewing or maintaining source code. The decimal form ± and hexadecimal form ± are equally valid alternatives that work in contexts where named entities may not be supported, or when generating HTML output programmatically from server-side code. All three representations produce identical visual output in every modern web browser.

Use the plus-minus sign to express measurement uncertainty (23.5 ± 0.2 kg), manufacturing tolerances (100 ± 5 mm), statistical confidence intervals, and mathematical expressions with dual solutions (x = ± 3). It is essential for scientific and engineering content on the web.