Epsilon in LaTeX (\epsilon)

Where it is used

Lowercase lunate epsilon ϵ, used for small positive quantities and error terms.

\epsilon prints the lunate form ϵ, while \varepsilon gives the open, curly form ε that many readers associate with handwritten epsilon. Analysts use either for an arbitrarily small number in \forall \epsilon > 0, but keep one form consistent throughout a paper. Many authors reserve \epsilon for small quantities and use \varepsilon for error terms or noise. Do not confuse either with the set membership sign \in, which looks similar to ϵ but is a relation with different spacing. Physics also uses \epsilon_0 for the vacuum permittivity.

Minimal compilable example

Paste this into an empty .tex file and compile it with pdfLaTeX, XeLaTeX or LuaLaTeX.

\documentclass{article}
\usepackage{amsmath}
\begin{document}
Epsilon: $\epsilon$

\[ \forall \epsilon > 0\ \exists N : n > N \implies |a_n - L| < \epsilon \]
\end{document}

Related symbols

• Epsilon (Variant)\varepsilon
• Delta (Upper)\Delta
• Zeta\zeta
• Delta\delta
• Eta\eta
• Gamma (Upper)\Gamma

Frequently asked questions

How do I write Epsilon in LaTeX?

Type \epsilon in math mode, for example $\forall \epsilon > 0\ \exists N : n > N \implies |a_n - L| < \epsilon$. It works in plain LaTeX without loading any package.

Which package do I need for \epsilon?

None. \epsilon is part of standard LaTeX, so it compiles with nothing in the preamble but the document class.

Can I use \epsilon in text mode, or only in math mode?

Only in math mode. Outside $...$ LaTeX stops with "Missing $ inserted", so write $\epsilon$ in running text. If you only need the glyph in text, paste the Unicode character ϵ instead (with XeLaTeX or LuaLaTeX and a font that has it).