Resize PDF to A4

Why mixed page sizes cause problems

A PDF can hold pages of different dimensions, and documents assembled from several sources routinely do - a Letter-size scan merged into an A4 report, an A3 drawing appended to a specification. On screen this is barely noticeable. At the printer it is where things go wrong: unexpected auto-scaling, margins that shift page to page, and on some devices a jammed tray.

Binding and print services almost always require a single page size, and many reject mixed-size files outright.

A4 versus Letter

A4 is 210 x 297 mm and standard everywhere except North America. Letter is 216 x 279 mm - slightly wider and noticeably shorter. The difference is small enough to look like a mistake rather than a choice, and large enough that content positioned near the bottom of a Letter page can fall outside an A4 print area.

Convert to whatever the destination expects. For India, Europe, and most of Asia and Africa that is A4.

Fit, Fill and Keep

Fit scales each page down until all of it is visible, which can leave a thin border where proportions differ. This is the safe default and the right choice for documents with text near the margins.

Fill scales up to cover the sheet and crops the overflow - acceptable for image-heavy pages, risky for anything with a page number or footer near the edge.

Keep original ratio does not scale at all, just re-centres the existing page on the new sheet. Use it when the content must stay at exact physical size, such as a technical drawing.

Text stays sharp

Resizing scales the page mathematically rather than resampling pixels, so text remains vector and stays crisp at any size. Embedded images are scaled too and can soften if enlarged substantially, which is one more reason Fit is usually the better choice than Fill.