Fix Page Size

Fit scales each page until the whole page sits inside the target size, centers it, and pads any leftover space with the background color. Fill scales until the target is completely covered, which crops whatever spills past the edges. Use Fit when losing content isn't acceptable and Fill when you'd rather have edge-to-edge pages.

Choose A4 as the target and keep Fit. Content is scaled proportionally, never stretched, so a Letter page ends up slightly narrower on A4 with a thin band of background color at the top and bottom. Page Dimensions will confirm every page matches afterward.

Auto looks at each page individually and keeps landscape pages landscape and portrait pages portrait, turning the target size to match. Portrait or Landscape forces every page into that orientation and scales the content to fit the new shape.

Choose Custom as the target and enter the width and height in inches or millimeters, down to a hundredth of a unit. This covers trim sizes that aren't in the preset list, such as 6 x 9 inch book pages.

Pages are redrawn as vector content in a new document, so text stays sharp and selectable and nothing is rasterized. What doesn't carry over: annotations, form fields, links, and bookmarks, because only the page appearance is copied. Run Flatten PDF first if filled-in form values need to survive.

Yes. Pick Letter and Fit; a page that is 8.49 by 11.02 inches is scaled by a fraction of a percent to exactly 8.5 by 11, which is invisible to the eye but satisfies print shops and document systems that reject off-size pages.

It fills the margins that Fit mode adds when the source page has a different shape than the target. White is the default; pick a dark color when your pages have dark backgrounds so the padding doesn't stand out.

No. The resizing is done by a PDF library running in your browser, and the new file is assembled on your device. Nothing is sent anywhere.