Print a Poster on Multiple Pages

1. Lay the sheets out by their numbers: the first number is the row, the second the column, so 1-1 is the top left.
2. On every sheet except those in the first column, cut off the left margin along the crop marks. On every sheet except the first row, cut off the top margin.
3. Lay each trimmed sheet over its neighbor so its edge meets the dashed line. That strip is the overlap, and it hides small differences between sheets.
4. Tape or glue from the back, one row at a time, then join the rows.

Print every sheet at 100 percent, also called Actual size. Fit to page shrinks each sheet a little and the marks stop lining up.

The tool never makes up pixels: the picture is spread over the whole poster as it is. A 12 megapixel phone photo is 4032 pixels wide. Over a 3x3 poster on A4 that gives about 137 dots per inch, which looks fine from a step away. On 5x5 it drops to about 83, so details look soft up close. For a poster you will see from a distance, that is usually enough.