When you're converting images to PDF, one of the first things you'll be asked is: A4, Letter, or Fit to Image? These options look like a minor detail, but choosing the wrong one can result in white borders where you didn't want them, cropped content, or a PDF that prints incorrectly. Here's what each one means and when to use it.
A4 — the international standard
A4 is 210 × 297 mm (8.27 × 11.69 inches). It's the standard paper size used in almost every country outside North America — Europe, Asia, Africa, Australia, South America. If you're submitting a document to a university, government agency, or employer in any of these regions, A4 is what they expect.
When you place an image on an A4 page, the image is scaled to fit within the A4 dimensions with the aspect ratio preserved. If your photo is landscape and the page is portrait, there will be white space above and below the image. This is normal and expected — it's just how a rectangular photo fits on a taller rectangular page.
Letter — the North American standard
Letter is 8.5 × 11 inches (215.9 × 279.4 mm). It's slightly wider than A4 but shorter. It's the default in the United States, Canada, and Mexico. If you're dealing with a US government form, a US university, or any American organization, they likely expect Letter-sized pages.
The difference between A4 and Letter is small enough that most documents look fine either way on screen. But when printing, a Letter-sized PDF on an A4 printer will either print with white margins or be scaled down slightly — and vice versa. For professional or official submissions, match the expected paper size.
Fit to Image — when you don't want any white space
Fit-to-Image (sometimes called "custom" or "exact image size") creates a PDF page that is exactly the same dimensions as the image. No white borders. The PDF page is the image.
This is the right choice when:
- You're converting photos to PDF and don't want any white space around them — for a photo book, a portfolio, or sending photos as a PDF attachment where the images should fill each page.
- The recipient will view the PDF on screen rather than print it, so paper size conventions don't apply.
- The images are different sizes and you want each PDF page to match its image exactly.
The downside: if you're printing this PDF, pages that don't match a standard paper size may cause printing dialog confusion or require manual scaling.
Portrait vs Landscape
Portrait means the page is taller than it is wide (the standard document orientation). Landscape means it's wider than it is tall. Most scanned documents and typed text documents are portrait. Presentations, wide photographs, and spreadsheets are often landscape.
When converting images to PDF, the orientation setting affects which direction the page is drawn — not the image itself. If your photo is landscape and you choose a portrait A4 page, the image will be placed (scaled to fit) on a tall portrait page, with white space on the sides or top and bottom depending on the image's proportions.
Quick decision guide
- Submitting a document in Indonesia, Europe, or most of the world → A4, Portrait.
- Submitting to a US or Canadian organization → Letter, Portrait.
- Converting personal photos into a PDF without white borders → Fit to Image.
- Unsure → A4. It's the global default and will be right more often than not.