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Last reviewed on May 7, 2026
The Delta symbol (δ) is one of the greek letters characters in the AllSymbols catalog. It is part of the Unicode Greek and Coptic block (U+0370–U+03FF). Greek letters serve double duty: they spell modern Greek and ancient Greek text, and they appear all through math, physics, statistics, and engineering as variable names with conventional meanings.
In technical writing, the letter is the variable; the meaning comes from your field’s convention. Pi (π) is the circle constant in geometry but a probability in statistics. Sigma (σ) is a standard deviation as a variable and a sum operator (Σ) when capitalized. Always introduce a Greek letter on first use unless your audience can be assumed to know the convention.
In Unicode, Delta sits at code point U+03B4. Web pages reference it with the HTML numeric entity δ; CSS rules reference it as a quoted hex escape (the four-digit code prefixed with a backslash); in JavaScript and most modern source-code contexts you can either paste the literal character or use a Unicode escape with the same hex digits.
Several Greek capitals look identical to Latin capitals (Alpha = A, Beta = B, Mu = M, Nu = N). They are distinct code points and may render with subtle differences. Use the Latin letter when you mean the Latin letter, and the Greek capital only when the meaning is specifically Greek — this matters for screen readers and search.
If Delta isn’t quite what you need, the Greek Letters page lists every related character on the site — including Alpha and Pi. The related-symbols grid below also surfaces the closest sibling characters.