Resize PDF

Most of the world prints on the A series defined by ISO 216. Its sizes all share the same proportions, so halving an A4 sheet gives A5 and doubling it gives A3, with nothing to crop or stretch. A4, 210 by 297 millimeters, is the everyday office and school size outside North America, A5 suits booklets and notes, and A3 is used for posters, plans and large tables.

The United States and Canada use inch-based sizes instead. Letter is 8.5 by 11 inches, a little wider and shorter than A4. Legal keeps the same width but is 14 inches long, for contracts and court papers, and Tabloid, 11 by 17 inches, is used for newspapers, posters and spreadsheets printed large. The table above lists the A sizes in both units, so you can compare them with the inch sizes at a glance.

Mismatched paper sizes cause small but annoying problems. A Letter document printed on A4 paper may lose a strip at the bottom or print with an odd margin; an A4 file sent to a US office may be shrunk by the printer driver. Some upload portals and print services also insist on one page size. Resizing the PDF itself avoids all of this, because the document then carries the right size wherever it goes.

Converting between the two systems is where resizing earns its keep. A4 is narrower and taller than Letter, so a page moved from one to the other cannot keep its exact proportions without either white bands or a slight crop. The difference is small, which is why Scale to fit usually looks natural: the content becomes a touch smaller and a narrow strip of white appears at the top and bottom or at the sides.

Custom covers everything else: a book trim size, a label, a card or a format required by a specific print shop. Enter the width and height and pick millimeters, centimeters or inches. Values can be large, so the same option also works for plans and banners.

Content decides what happens to each page's content on its new sheet. Scale to fit enlarges or reduces the content until the whole page is visible on the new size. When the proportions differ, as between Letter and A4, a thin white band appears on two sides. It is the safe default, because nothing is ever cut off.

Fill page scales the content until it covers the entire new page. There are no white bands, but where the proportions differ, a little is cropped from two edges. It suits full-bleed designs, photos and slides, and is risky for documents with text close to the edge. Keep size does not scale at all: the content stays at its original size and is placed on the new sheet, which is useful when you want to put a small page, such as a receipt or a label, on a standard sheet without enlarging it.

Position decides where the content sits when it does not cover the whole page: centered, at the top center, in the top-left corner, or at the bottom center. Top-left is handy for small items that will be cut out after printing, and centered looks best for most documents.

Margin keeps a white border of the width you set around the content on every side. Zero uses the full page. Most office and home printers cannot print to the very edge of the paper, so a few millimeters of margin keep page numbers and footers from being cut off.

Orientation is set to Auto by default, which keeps each page the way it was. A landscape chart in a portrait report becomes a landscape page of the new size, rather than being shrunk onto a portrait sheet. Choose Portrait or Landscape to force every page into one orientation, for example when a print service wants a uniform document.

Apply to limits the change to the pages you list. A report with a single oversized fold-out plan can have just that page brought down to A4 or Letter, while the rest stays untouched. Page numbers are positions in the file, counted from 1, so check the page box in your viewer rather than the printed footer.

If a page is turned the wrong way rather than sized wrongly, resizing is not the fix. Straighten it with the Rotate PDF tool first, then resize, so Auto orientation sees each page the right way up.

Mixed documents are common. A scanned application might combine A4 letters, a Letter-sized bank statement and a phone photo of an ID card with no standard size at all. Resizing every page to one size with Scale to fit and a small margin turns that collection into a document that prints evenly, and Auto orientation keeps any landscape page readable.

The word resize means different things to different people. Here it means the physical page size, the size of the sheet the document prints on. It does not change how many kilobytes the file takes. A PDF with A3 pages resized to A5 is roughly as heavy as before, because the same text, fonts and pictures are still inside.

Text stays text after resizing, since the pages are not turned into images, so the resized document can still be searched, copied and read aloud by a screen reader. Several files in one batch all receive the same page size and placement settings, and each comes back as its own PDF, so a folder of mixed documents can be brought to one paper size in a single run.

If an upload form rejects the file because it is too large in MB, Compress PDF is the tool you need. If a form rejects it for being too small, which some government portals do, Increase PDF Size adds bytes without changing the pages. And when a set of files with different page sizes needs to become one document, the Merge PDF tool can match their page sizes while combining them.

Scaling vector content is lossless: text, lines and charts are redrawn at the new size and stay sharp. Scanned pages are pictures, so they keep the detail they were scanned with. Reducing them is fine, and enlarging a scan far beyond its original paper size shows soft edges, just as enlarging a photo would.

When you print a resized file, turn off the printer's own Fit to page or similar scaling option if the PDF already has the right paper size and margin, so the driver does not scale it a second time.