\phantom & \vphantom & \hphantom (LaTeX2e unofficial reference manual (November 2018))

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#### 16.6.2 `\phantom` & `\vphantom` & `\hphantom`

Synopsis:

    \phantom{subformula}

or

    \vphantom{subformula}

or

    \hphantom{subformula}

The `\phantom` command creates a box with the same height, depth, and width as subformula, but empty. That is, this command causes LaTeX to typeset the box but not its ink. The `\vphantom` variant also produces an invisible box with the same height and depth as subformula, but it has width zero. And `\hphantom` makes a box with the same width as subformula but with height and depth zero.

Without the `\vphantom` in this example, the top bars of the two square roots would be at different heights.

    \( \sqrt{\vphantom{a^3}a}\cdot\sqrt{a^3} \)

The `\vphantom{a^3}` causes the first `\sqrt` to have inside it a box of the same height as the second `\sqrt`, so LaTeX makes the bars align.

These commands often are combined with `\smash`. See \smash for another example of the use of `\vphantom`.

The three phantom commands appear often but note that LaTeX provides a suite of other commands to work with box sizes that may be more convenient, including `\makebox` (see \mbox & \makebox) as well as `\settodepth` (see \settodepth), `\settoheight` (see \settoheight), and `\settowidth` (see \settowidth). In addition, the `mathtools` package has many commands that offer fine-grained control over spacing.

All three commands produce an ordinary box, without any special mathematics status. So to do something like attaching a superscript you should give it such a status, for example with the `\operatorname` command from the package `amsmath`.

While most often used in mathematics, these three can appear in other contexts. However, they don’t cause LaTeX to change into horizontal mode. So if one of these starts a paragraph then you should prefix it with `\leavevmode`.

Unofficial LaTeX2e reference manual