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How to Write a Subscript in LaTeX

In math mode, _ makes a subscript and ^ a superscript: $x_1$, $x^2$. Each takes only the next character, so wrap longer scripts in braces: $x_{i+1}$, $e^{-x^2}$. Write both on one symbol as $x_i^2$.

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Script syntax

  • x_1
    x 1

    Subscript of one character.

  • x^2
    x 2

    Superscript (exponent) of one character.

  • x_{i+1}
    x i + 1

    Braces for a subscript longer than one character.

  • x^{n-1}
    x n − 1

    Braces for a longer superscript.

  • x_i^2
    x i 2

    Subscript and superscript on the same symbol.

  • x_{\text{max}}
    x max

    Upright word as an index (amsmath).

  • a^{b^{c}}
    a b c

    Nested superscripts.

  • {}^{14}_{6}\mathrm{C}
    6 14 C

    Scripts on the left, e.g. isotopes.

  • H\textsubscript{2}O
    Text mode, no math preview

    Subscript in normal text (built into LaTeX since 2015).

  • 1\textsuperscript{st}
    Text mode, no math preview

    Superscript in normal text, e.g. ordinals.

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Templates

Subscripts and superscripts examples

Each result below is drawn from the LaTeX under it. Copy the code, edit it on this page, or open it in the full editor.

  • Sequence and recurrence

    a n + 1 = 2 a n + 1
    LaTeX
    a_{n+1} = 2a_n + 1
    Edit hereOpen in editor

  • Exponent with braces

    e − x 2 / 2
    LaTeX
    e^{-x^2/2}
    Edit hereOpen in editor

  • Double index

    A i j = a i , j
    LaTeX
    A_{ij} = a_{i,j}

    Add a comma when the indices could be misread: a_{i,j}.

    Edit hereOpen in editor

  • Chemical formula

    H 2 O + CO 2
    LaTeX
    \mathrm{H_2O} + \mathrm{CO_2}

    \mathrm keeps element symbols upright.

    Edit hereOpen in editor

  • Tensor-style indices

    T μ ν = g μ α g ν β T α β
    LaTeX
    T^{\mu\nu} = g^{\mu\alpha} g^{\nu\beta} T_{\alpha\beta}
    Edit hereOpen in editor

  • Prime with an exponent

    f ′ ( x ) 2 f ″ ( x )
    LaTeX
    f'(x)^2 \quad f''(x)

    ' is already a superscript, so f'^2 works too.

    Edit hereOpen in editor

  • Limits of a sum

    ∑ i = 1 n x i 2
    LaTeX
    \sum_{i=1}^{n} x_i^2

    On big operators _ and ^ set the limits below and above.

    Edit hereOpen in editor

How subscripts and superscripts work

_ and ^ only exist in math mode and apply to the single character or group that follows. x^10 therefore prints x¹ followed by 0; write x^{10}. Anything more than one character — numbers, expressions, commands with arguments — goes in braces.

The order does not matter: x_i^2 and x^2_i give the same result. Scripts stack neatly on the same symbol. To stagger them (tensor notation), use an empty group: T^{a}{}_{b}.

Text in subscripts and scripts outside math

Letters in a subscript are italic variables. For a label such as "max" or "eff", use x_{\text{max}} (amsmath) or x_{\mathrm{max}} so it is upright and correctly spaced.

In normal text use \textsubscript{…} and \textsuperscript{…} — for example CO\textsubscript{2} or 21\textsuperscript{st} century. For chemistry, the mhchem package's \ce{H2O} handles subscripts automatically.

Common mistakes

  • Without braces only the first character is raised, giving x¹0.

    Instead of
    x^10
    Write
    x^{10}

  • Two subscripts on one symbol raise "Double subscript". Nest them or put both in one group.

    Instead of
    x_i_j
    Write
    x_{i_j}  or  x_{ij}

  • "Double superscript": make the grouping explicit.

    Instead of
    x^2^3
    Write
    {x^2}^3  or  x^{2^3}

  • Only "m" becomes the subscript, and "ax" follows as italic variables.

    Instead of
    v_max
    Write
    v_{\text{max}}

In Overleaf, MathJax and Word

  • Overleaf and pdfLaTeX

    _ and ^ are built in; \text needs amsmath. Using them outside math gives "Missing $ inserted" — often from an underscore in a file name or URL; write \_ there.

  • MathJax and KaTeX

    MathJax and KaTeX use the same _ and ^ rules and braces. \textsubscript and \textsuperscript are not available; write the formula in math mode instead. Some Markdown apps treat _ as italics, so keep formulas inside $ … $.

  • Microsoft Word

    In a Word equation, x_2 or x^2 followed by a space becomes a real subscript or superscript. For normal text, Word's shortcuts are Ctrl+= (subscript) and Ctrl+Shift+= (superscript) on Windows.

Subscripts and superscripts in LaTeX: questions

How do I write a subscript in LaTeX?
Use an underscore in math mode: $x_1$. For more than one character, use braces: $x_{12}$ or $x_{\text{max}}$.
How do I write a superscript or exponent?
Use a caret: $x^2$. Put longer exponents in braces: $2^{10}$, $e^{i\pi}$.
How do I put a subscript and superscript on the same letter?
Write both: $x_i^2$. They stack on top of each other.
How do I write a subscript outside math mode?
Use \textsubscript{2}, e.g. H\textsubscript{2}O, or wrap it in math: H$_2$O.
Why does x^10 only raise the 1?
^ takes one character. Use braces: x^{10}.

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