Printer printer = Printer.getDefaultPrinter();
        PageLayout pageLayout = printer.createPageLayout(Paper.A4, PageOrientation.PORTRAIT, Printer.MarginType.DEFAULT);
double scaleX = pageLayout.getPrintableWidth() / node.getBoundsInParent().getWidth();
double scaleY = pageLayout.getPrintableHeight() / node.getBoundsInParent().
node.getTransforms().add(new Scale(scaleX, scaleY));
PrinterJob job = PrinterJob.createPrinterJob();
if (job != null) {
    boolean success = job.printPage(node);
    if (success) {
        job.endJob();
    }
}

pageLayout.getPrintableWidth()
pageLayout.getPrintableHeight()