PDF parameters

A template's params.json controls how the browser prints the page to PDF. All fields are optional; unset fields use the browser's defaults. These map to the Chrome DevTools Page.printToPDF parameters.

Full example

{
  "pdf": {
    "landscape": false,
    "printBackground": true,
    "preferCSSPageSize": false,
    "scale": 1.0,
    "paperWidth": 8.27,
    "paperHeight": 11.69,
    "marginTop": 0.4,
    "marginBottom": 0.4,
    "marginLeft": 0.4,
    "marginRight": 0.4,
    "waitLifecycleEvent": "load"
  }
}

Fields

Key	Type	Meaning
landscape	bool	Landscape orientation.
printBackground	bool	Print background graphics/colors.
preferCSSPageSize	bool	Let a CSS @page size win over paperWidth/paperHeight.
scale	number	Rendering scale factor.
paperWidth	number	Paper width, inches.
paperHeight	number	Paper height, inches.
marginTop / marginBottom / marginLeft / marginRight	number	Margins, inches.
waitLifecycleEvent	string	Which page event to await before printing. See Lifecycle events.

Note: the JSON keys are lowercase (scale, not Scale). A capitalized key is ignored and the default is used.

Page size via CSS

Instead of paperWidth/paperHeight, you can size pages from CSS and set preferCSSPageSize: true:

@page { size: A4; margin: 12mm; }

This is often the cleanest approach for print-specific layouts, and lets you use @page :first, named pages, and page breaks (break-after: page).

Defaults

Without params.json, the browser's letter-size defaults apply and the renderer waits for the load event. Set only the fields you need to change.