How PDF N-up (pages per sheet) works
PDF N-up prints multiple pages onto a single sheet by scaling and arranging them in a grid. You can choose layouts of 2, 4, 6, 8, 9 or 16 pages per sheet. The tool re-renders each original page into a cell of the output sheet using pdf-lib inside your browser. No file is uploaded; the layout computation runs entirely on your device.
Each original page is scaled proportionally to fit its cell in the output grid. The output sheet size is configurable (A4, Letter, and others) so you can match your printer. A 2-up layout places two pages side by side in landscape; a 4-up places four in a 2x2 grid. For documents intended for print, this approach cuts paper consumption in half or more. The output is a standard PDF that prints correctly from any PDF viewer.