2-up and 4-up place multiple source pages onto one output sheet
2-up places two source pages on each sheet; 4-up places four. This tool supports 2, 4, 6, or 9 pages per A4 or Letter sheet.
Each source page keeps its aspect ratio while being fitted into its cell, so unused space can remain around it.
N-up is not the same thing as booklet imposition
N-up keeps pages in normal sequence and simply places several on each sheet. Booklet printing requires a different page order so pages pair correctly after folding.
For booklet page order, use a separate imposition workflow such as Booklet imposition order generator.
Margins are entered in points: 18 pt is about 6.35 mm
PDF uses 72 pt = 1 inch. A margin of 18 pt equals 0.25 inch, or about 6.35 mm. Increasing the margin reduces the area available for each source page.
A zero margin is allowed, but the physical printer may still have a non-printable edge area.
Avoid applying N-up a second time in the print dialog
If you create an N-up PDF here and then also choose “2 pages per sheet” in the printer driver, the document can be reduced a second time.
When printing an already imposed file, check the printer’s page-layout settings before starting the job.