JPG to PDF A4

A4 (210×297mm) is the standard paper size across essentially every country outside North America, while the United States, Canada and a handful of other countries use Letter (8.5×11 inches) instead — the two are close in proportion but not identical, and a document formatted for one prints with different margins on the other. Because paper size is set by local convention rather than by anything about the document itself, the correct choice generally follows wherever the document is headed rather than wherever it is being created — a form destined for a European institution should be A4 regardless of what size paper a US-based sender might default to, and vice versa.

This matters specifically for anything that will actually be printed. For a PDF that only needs to display on a screen, the page size has essentially no visual consequence and either would do; the distinction becomes concrete the moment a physical printer and a specific sheet of paper enter the picture.

Government forms, university applications, visa paperwork and most institutional uploads outside the US, Canada and a handful of other countries assume A4 even when the upload page never says so explicitly, because it is simply the paper size the institution itself uses and prints on. A document submitted at Letter size to an A4-expecting system usually still opens and displays fine on screen, but can crop or misalign when the recipient prints it, since the two sizes differ enough that content near the edges lands differently on the physical page.