What each setting changes
A page margin reduces the area available to print the picture. Overlap reserves a repeated strip between neighbouring tiles. Increasing either can increase the number of sheets. A deliberate white grid changes the appearance of the assembled image.
With A4 portrait paper and 10 mm margins, the inner rectangle is 190 × 277 mm before accounting for overlap and assembly details. Multiplying 210 × 297 mm by the grid count will not give the exact image dimensions.
Find a safe margin for your printer
- Check the manual for your exact printer, paper size and media type. Minimum printable edges may differ between the leading, trailing and side edges.
- Begin with the tool’s 10 mm margin and print the test ruler and neighbouring tiles. This is a conservative starting setting, not a guarantee for every printer.
- If you want smaller margins, reduce them gradually and check every edge for missing guides or image content.
- Keep scale at 100%. If the printer warns about clipping, enlarge the PDF margin rather than silently accepting automatic shrink.
Borderless does not mean dimensionally unchanged
A borderless mode may enlarge the image beyond the sheet so no white sliver remains. That can crop content and alter an exact-size template. Availability also depends on the printer, selected paper size and media.
For a seamless tiled poster, an ordinary bordered print with trimmed overlap is often easier to verify. Zero PDF margin by itself does not enable borderless hardware.
Choose the right fix
Missing outer content: increase the page margin or select a genuinely supported print mode. Too many sheets: compare orientation, final size and overlap before reducing margins. White seams after assembly: check trimming and alignment first.
Intentional grid bands should remain visible. Do not remove them merely because they resemble printer margins.