Best PDF Page Size: A4 vs Letter vs Fit — Which Should You Choose?

Choosing between A4, Letter and Fit takes about ten seconds once you know one fact: A4 and Letter are fixed paper sizes built for printing, while Fit builds each page around your image. Match the page size to where the PDF is actually going, paper or screen, and the right choice makes itself.

Get it wrong and nothing breaks dramatically. You just get pages shrunk to 94 percent, a clipped signature line, white bands around a photo that should have filled the screen, or a document that looks faintly off next to everyone else's. This guide gives you the exact dimensions, the pixel counts behind them, and a reliable rule for every common job.

The Exact Dimensions, Side by Side

PDF pages are measured internally in points, 72 points to an inch, but millimetres and inches are easier to think in. The pixel column assumes 300 DPI, the standard resolution for sharp print.

Page size	Millimetres	Inches	Pixels at 300 DPI
A4	210 x 297 mm	8.27 x 11.69 in	2480 x 3508 px
US Letter	216 x 279 mm	8.5 x 11 in	2550 x 3300 px
Fit	Matches your image	Matches your image	Matches your image

The numbers explain the quiet trouble these two sizes cause. A4 is 6 mm narrower than Letter but 18 mm taller, and it carries about 3.5 percent more area. Print an A4 document on Letter paper at 100 percent and the extra height has nowhere to go: the printer either crops the bottom or shrinks the whole page to roughly 94 percent. Print Letter on A4 and the sides get squeezed instead. Neither result is unreadable, but your text ends up smaller than designed and your margins drift from what you set.

Fit has no fixed row in the table because it copies your image's shape exactly. A 4:3 photo gets a 4:3 page, a tall phone screenshot gets a tall page, and a panorama gets a wide one. Nothing is padded, stretched, or cropped.

A4: The World Standard

A4 belongs to the ISO 216 system used across Europe, Asia, Africa, Australia, and most of Latin America. Schools, banks, government offices, and employers in those regions stock A4 paper, ship printers with A4 as the default, and expect A4 uploads.

Choose A4 when:

• The recipient is outside North America, or a portal asks for A4 by name
• Your printer tray holds A4 and the document will actually be printed
• You are submitting a CV, invoice, certificate, or application internationally
• You want a uniform, formal document where every page matches

A useful detail: because A4 is taller, it fits slightly more text per page than Letter at the same font size, which is one reason reports and academic papers favour it. Students preparing coursework will find worked examples in our guide to JPG to PDF for students and assignments.

US Letter: The North American Standard

US Letter is the everyday office size in the United States and Canada. At 216 x 279 mm it is a little wider and noticeably shorter than A4, which gives pages a broader, less dense feel. American printers, copiers, binders, sheet protectors, and filing cabinets are all built around it.

Choose Letter when:

• You live in the US or Canada, or the file is going there
• An American employer, court, school, or agency supplied the form
• The PDF will be printed and filed alongside other Letter documents
• A US-based portal or application specifies 8.5 x 11 inches

Neither size is better in the abstract. The correct one is simply the one that matches the paper and expectations at the other end. A mismatched file usually still prints, because printer drivers shrink to fit by default, but you lose control over the final scale, and small print on forms can end up genuinely small.

Fit: The Page That Follows Your Image

Fit reverses the logic. Instead of dropping your image into a fixed page and filling the leftover space with white, it sizes the page to the image, pixel for pixel in proportion. Faces are never stretched, screenshots keep their exact shape, and there are no empty bands.

Fit is the right choice when:

• The PDF will be read on phones, tablets, or laptops rather than printed
• You are combining mixed shapes, portrait, landscape, and square images in one file
• The images are photos, receipts, whiteboard shots, or screenshots with no natural paper size
• You want each image full-bleed, edge to edge, with no border

The trade-off is formality and print predictability. A Fit document can have a different page size on every page, which looks natural on screen but confuses a print run: the printer must rescale each page to the loaded paper, and results vary. If every page must print identically on one paper stock, pick the fixed size instead. For more on merging mixed batches well, see how to combine multiple JPGs into one PDF.

Orientation: Auto, Portrait, or Landscape

Page size and orientation work as a pair. Portrait is taller than wide, landscape is wider than tall, and Auto simply matches each page to its image. Auto is the correct default for almost everyone: a wide photo lands on a wide page instead of being shrunk onto a tall one with bands above and below.

Set Portrait manually when every page must be tall, such as a report or a stack of scanned forms. Set Landscape for slide-style documents or wide screenshots you want to keep together. The classic mistake is forcing Portrait on a mixed batch, which does not crop anything but shrinks wide images far more than readers expect. A two-second check of the first wide page in the preview prevents it.

How Margins Change the Result

Margins do not change the page size. They change how much of that page your image is allowed to use, and they exist mainly because of printer hardware: most home and office printers cannot print within about 3 to 5 mm of the paper edge, so edge-to-edge content risks being clipped.

• None: the image fills the page completely. Best for photos viewed on screen and for Fit pages. On paper, expect a hairline of white or slight clipping unless your printer genuinely supports borderless printing.
• Small: the balanced default for documents. It keeps text and signature lines safely inside the printable area while using nearly all of the page.
• Big: a deliberate document frame. Use it for certificates, formal letters, and scans with handwriting close to the edges that must never be trimmed.

On a Fit page, a margin simply adds a uniform border around the image while the page grows to hold it, so the image itself is never reduced. On A4 or Letter, a margin shrinks the image slightly to fit inside the safe area. If a scan already has generous white space around the text, None is fine; the page's own blank edges act as the margin.

Quick Recommendations by Job

• Printing at home or work: A4 or Letter, whichever paper is in the tray, with a small margin
• Sharing photos with family: Fit, no margin, Auto orientation
• Submitting a form or application: the exact size named in the instructions, almost always A4 or Letter, portrait
• Scanning paper documents: the size of the paper you photographed, so the PDF mirrors the original
• Portfolio or lookbook: Fit for screen viewing, A4 landscape if it will be printed as a book
• Saving screenshots: Fit, so tall phone screenshots are never squeezed onto a wide page

The Rule Worth Remembering

If the PDF will be printed on standard paper, choose that paper's size. If it will live on screens, choose Fit. If someone gave you instructions, follow their stated size exactly, even if it is not your local standard. That one rule resolves nearly every real-world case.

Ready to test it? Open the free JPG to PDF converter, add your images, and flip between A4, Letter, and Fit in the preview to see the difference on your own files. Everything runs in your browser, your images are never uploaded, there is no sign-up and no watermark, and you can change your mind as often as you like before downloading.