Field guide
DPI and how big a split image can print
DPI metadata is an instruction about physical scale. The available image detail still comes from dividing actual pixel dimensions across the intended inches.
01
The poster print size calculator on this site does these sums before a picture is opened: sheets to finished size, pixels to the largest print at 300, 200 and 150 DPI, and a finished size to the number of sheets each paper needs.
02
Calculate pixels per inch after choosing the assembled width and height. A split operation changes page boundaries, not the source pixel count.
03
Use viewing distance to set a realistic target. A wall poster can look convincing at 120–180 ppi where a hand-held print would reveal softness.
04
Upscaling before tiling gives the printer more samples but not more captured information. Inspect faces, lettering and diagonal lines for interpolation artefacts.
05
Keep one unsplit master. Reassembling individually compressed tiles later introduces seams and makes any change to poster size needlessly difficult.
