### 4.1.2 Paper size and automatic scaling

#### Setting the paper size

‘A4’ is the default value when no explicit paper size is set. However, there are two functions that can be used to change it:

`set-default-paper-size`

  >     #(set-default-paper-size "quarto")

  which must always be placed at the toplevel scope, and

`set-paper-size`

  >     \paper {
  >       #(set-paper-size "tabloid")
  >     }

  which must always be placed in a `\paper` block.

If the `set-default-paper-size` function is used in the toplevel scope, it must come before any `\paper` block. `set-default-paper-size` sets the paper size for all pages, whereas `set-paper-size` only sets the paper size for the pages that the `\paper` block applies to. For example, if the `\paper` block is at the top of the file, then it will apply the paper size to all pages. If the `\paper` block is inside a `\book`, then the paper size will only apply to that book.

When the `set-paper-size` function is used, it must be placed before any other functions used within the same `\paper` block. See Automatic scaling to paper size.

Paper sizes are defined in ‘`scm/paper.scm`’, and while it is possible to add custom sizes, they will be overwritten on subsequent software updates. The available paper sizes are listed in Predefined paper sizes.

The following command can be used in the file to add a custom paper size which can then be used with `set-default-paper-size` or `set-paper-size` as appropriate,

>     #(set! paper-alist (cons '("my size" . (cons (* 15 in) (* 3 in))) paper-alist))

>     \paper {
>       #(set-paper-size "my size")
>     }

The units `in` (inches), `cm` (centimeters) and `mm` (millimeters) can all be used.

If the symbol `'landscape` is added to the paper size function, pages will be rotated by 90 degrees, and wider line widths will be set accordingly.

>     #(set-default-paper-size "a6" 'landscape)

Swapping the paper dimensions without having the print rotated (like when printing to postcard size, or creating graphics for inclusion rather than a standalone document) can be achieved by appending ‘`landscape`’ to the name of the paper size itself:

>     #(set-default-paper-size "a6landscape")

When the paper size ends with an explicit ‘`landscape`’ or ‘`portrait`’, the presence of a `'landscape` symbol only affects print orientation, not the paper dimensions used for layout.

#### See also

Notation Reference: Automatic scaling to paper size, Predefined paper sizes.

Installed Files: ‘`scm/paper.scm`’.

#### Automatic scaling to paper size

If the paper size is changed with one of the scheme functions (`set-default-paper-size` or `set-paper-size`), the values of several `\paper` variables are automatically scaled to the new size. To bypass the automatic scaling for a particular variable, set the variable after setting the paper size. Note that the automatic scaling is not triggered by setting the `paper-height` or `paper-width` variables, even though `paper-width` can influence other values (this is separate from scaling and is discussed below). The `set-default-paper-size` and `set-paper-size` functions are described in Setting the paper size.

The vertical dimensions affected by automatic scaling are `top-margin` and `bottom-margin` (see Fixed vertical spacing `\paper` variables). The horizontal dimensions affected by automatic scaling are `left-margin`, `right-margin`, `inner-margin`, `outer-margin`, `binding-offset`, `indent`, and `short-indent` (see Horizontal spacing `\paper` variables).

The default values for these dimensions are set in ‘`ly/paper-defaults-init.ly`’, using internal variables named `top-margin-default`, `bottom-margin-default`, etc. These are the values that result at the default paper size `a4`. For reference, with `a4` paper the `paper-height` is `297\mm` and the `paper-width` is `210\mm`.

#### See also

Notation Reference: Fixed vertical spacing `\paper` variables, Horizontal spacing `\paper` variables.

Installed Files: ‘`ly/paper-defaults-init.ly`’, ‘`scm/paper.scm`’.

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