The Ratio Symbol ∶ (U+2236)
The ∶ symbol, known officially in Unicode as the Ratio symbol (U+2236), is a mathematical operator used to express the proportional relationship between two numbers. While it looks almost identical to a standard punctuation colon, the Ratio symbol is specifically formatted to align correctly with mathematical equations. It sits squarely on the "math axis"—meaning it centers vertically alongside numbers and operators like the plus or minus sign—rather than resting low on the text baseline.
Originating from early algebra and proportional mathematics, the ratio symbol helps visually distinguish mathematical operations from standard grammatical text. You will find it in the Mathematical Operators Unicode block under the code point U+2236. Because standard colons drop low to match lowercase letters, typographers and mathematicians prefer U+2236 to keep equations visually balanced and perfectly spaced.
In mathematics, chemistry, and physics, ∶ expresses a strict ratio, such as comparing parts of a whole (like a 3∶1 mix of water to syrup or a gear ratio in mechanics). Programmers and web designers often rely on the true ratio symbol when typesetting complex formulas online using LaTeX, MathML, or specialized font rendering. However, in casual social media posts, messaging, and everyday typing, most people just hit the standard colon key. You rarely spot the dedicated ratio symbol outside of digital textbooks, academic papers, or coding environments that require strict mathematical syntax.
Typing the ∶ symbol takes a little extra effort since it lacks a dedicated keyboard key. On Windows, you can type 2236 and press Alt + X in word processors like Microsoft Word, or find it in the Character Map. Mac users can press Control + Command + Space to open the Character Viewer and search for "ratio." If you are writing HTML for a website, simply use the decimal code ∶ or the hex code ∶ to ensure it renders flawlessly across all modern browsers.
It is incredibly easy to confuse ∶ with the standard keyboard colon : (U+003A), but they serve entirely different roles. The punctuation colon introduces lists, separates hours and minutes, or builds simple text emoticons, while the ratio symbol strictly connects numerical values. Another close relative in the Unicode catalog is the Proportion symbol ∷ (U+2237), which looks like a double colon and is used to indicate equality between two different ratios.