A4 vs Letter vs Image Size for JPG to PDF

When you convert JPG images to PDF, the page size determines the physical or displayed dimensions of each PDF page. A4 is the standard paper size in most countries outside North America, Letter is standard in the United States and Canada, and Image size makes the page match the image’s own pixel dimensions. With the TIG Tools JPG to PDF converter, you can choose A4, Letter, or Image size, set the orientation, and control margins in one pass.

A4 vs Letter vs Image Size: What the Options Mean

The page size option you choose affects how large the PDF page is, how much white space appears around the image, and how the file prints. The three common choices are easy to compare once you know the actual dimensions.

Page size option	Actual dimensions	Best for
A4	210 × 297 mm (8.27 × 11.69 in)	Most countries outside North America; scanned documents, forms, letters for printing
Letter	8.5 × 11 in (215.9 × 279.4 mm)	United States, Canada, and some nearby markets; business documents and school papers
Image size	Derived from the image’s pixel dimensions, often mapped at 72 or 96 pixels per inch	Screen-only PDFs, exact image canvases, photo collections where you do not need a standard paper size

A4 follows the ISO 216 international paper size standard. Letter is the de facto standard paper size in the United States and Canada. They are close but not interchangeable: Letter is slightly wider and shorter than A4, while A4 is narrower and taller.

A4 vs Letter: Dimensions, Aspect Ratio, and Region

A4 measures 210 × 297 mm and has an aspect ratio of 1:√2, approximately 1:1.414. That is the property of ISO 216 paper sizes: when you cut or fold an A-series sheet in half, the proportions stay the same.

Letter measures 8.5 × 11 inches, which is 215.9 × 279.4 mm, and has an aspect ratio of approximately 1:1.294. Compared with A4, Letter is wider by about 5.9 mm and shorter by about 17.6 mm.

Why this matters for JPG to PDF:

• An image scaled to fill A4 will leave slightly different white space on Letter.
• A scanned A4 document placed on a Letter page will be slightly reduced or will leave uneven margins.
• A US Letter form placed on an A4 page can have extra space at the bottom or reduce the original content size.

If you are preparing a document for printing or formal submission, match the page size to the paper used in your region. For most of Europe, Asia, Africa, Oceania, and many other countries, choose A4. For the US and Canada, choose Letter.

Orientation: Portrait vs Landscape for JPG to PDF

Orientation describes which side of the page is longer.

• Portrait means the page is taller than it is wide. It suits vertical photos, scanned documents, and text pages.
• Landscape means the page is wider than it is tall. It suits horizontal photos, screenshots, slides, and wide graphics.

In a JPG to PDF conversion, the converter normally scales the whole image to fit inside the chosen page while preserving the image’s aspect ratio. If the page orientation does not match the image orientation, you usually get white bars on two sides. For example, a wide landscape photo placed on an A4 portrait page will be shrunk to the page width and will show large white areas above and below.

If your image is landscape and you want the photo to fill more of the page, choose Landscape for A4 or Letter. If the image is portrait, choose Portrait. If the tool lets you convert mixed-orientation images, check the preview to see how each page will look.

Margin Settings: How They Change the Output

Margins add white space between the image and the edge of the PDF page. Common margin options are None, Small, Medium, and Large, or custom values.

• None or zero margin places the image as close to the page edge as the tool allows. This is usually best for photos and full-page scans when exact size matters.
• Small or medium margins add a clean white frame. This is useful for documents that will be printed and bound or hole-punched.
• Large margins shrink the image noticeably. Use them only when you want a deliberately small image on a larger page.

If you choose A4 or Letter with margins, the image fits within the printable area inside the margins, so the image is effectively reduced. If you choose Image size with a margin, the result may either add to the page size or shrink the image within the page, depending on how the converter implements margins. For the most predictable Image size output, choose None or zero margin.

Step-by-Step: Using TIG Tools JPG to PDF

Follow these steps to convert JPGs with the right page size, orientation, and margins.

1. Open the JPG to PDF tool.
2. Upload one or more JPG images. If you upload several images, they normally become pages in the uploaded order.
3. Choose the page size: A4, Letter, or Image size.
4. Set the orientation to Portrait or Landscape based on the majority of your images.
5. Choose a margin setting. Start with None if you want full-size output, or Small for documents.
6. Check the preview or page order if available.
7. Start the conversion and download the resulting PDF.

If you need to combine the result with other PDFs later, use Merge PDF after conversion.

Worked Examples

Example 1: Scanned A4 document in Europe

You scan an A4 contract at 300 DPI and get a 2480 × 3508 pixel JPG. The correct choice is A4, Portrait, and None or Small margins. The PDF page will match A4 paper, and the scan will print at the expected size.

If you choose Image size instead, the result depends on how the tool maps pixels to PDF points. At 72 pixels per inch, a 2480 pixel wide image becomes a 34.4 inch wide page. At 300 DPI, it would match A4 closely. Because that depends on the tool and image metadata, A4 is the safer choice.

Example 2: US Letter form or invoice

You photograph or scan a US Letter invoice and get a 2550 × 3300 pixel image at 300 DPI. Choose Letter, Portrait, and None or Small margins. The PDF will match standard US paper and print without unwanted scaling.

Example 3: Smartphone photo or screenshot for screen viewing

You have a 1920 × 1080 screenshot from a presentation. If you choose Image size with no margins, the PDF page may be treated as 26.7 × 15 inches at 72 pixels per inch, which is much larger than a standard page. That can be fine for screen viewing but confusing for printing.

For a cleaner result, choose A4 Landscape or Letter Landscape. The screenshot will be scaled down to fit the page and remain easy to read. If you want the PDF page to exactly match the screenshot’s pixel dimensions, choose Image size and no margins.

Tips and Common Mistakes

• Match the page size to the region. Use A4 for most non-US printing and Letter for US or Canadian documents.
• Do not use Image size for print documents unless you know the result. Standard page sizes remove guesswork.
• Match orientation to the image. A landscape image on a portrait page creates large white bars; the reverse also wastes space.
• Avoid large margins on full-size scans. Margins shrink the image and may make fine text harder to read.
• Preview before downloading. If the tool shows a preview, check that the image is not cropped or overly small.
• Resize very large images first. If Image size produces an enormous PDF page, use Image Resizer to reduce the pixel dimensions before conversion.
• Compress after conversion if needed. Image-heavy PDFs can be large; Compress PDF reduces file size after you create the file.

Summary

• A4 is 210 × 297 mm and is the standard paper size in most countries outside North America.
• Letter is 8.5 × 11 inches and is the standard paper size in the US and Canada.
• Image size sets the PDF page from the image’s pixel dimensions and is best for screen-only or exact-canvas use.
• Set Portrait for tall images and Landscape for wide images to reduce unwanted white space.
• Use None or zero margins for full-size output, and choose A4 or Letter for predictable printing.

Frequently asked questions

What is the difference between A4 and Letter page size?

A4 is 210 × 297 mm, the ISO 216 standard used in most countries outside North America. Letter is 8.5 × 11 inches, used mainly in the US and Canada. Letter is slightly wider and shorter than A4.

When should I choose Image size instead of A4 or Letter?

Choose Image size when you want the PDF page to match the image’s pixel dimensions directly, such as for screen-only PDFs or exact photo canvases. For printing or formal documents, A4 or Letter is usually a safer choice.

Which orientation should I use for JPG to PDF?

Use Portrait for tall images or documents and Landscape for wide images or screenshots. Matching the page orientation to the image reduces white bars and makes better use of the page.

How do margins affect a JPG to PDF conversion?

Margins add white space around the image on the PDF page. None or zero margins keep the image close to the page edge, while small, medium, or large margins shrink the image inside the page.

Why does my PDF page look huge when I choose Image size?

The tool may map image pixels to PDF points at 72 or 96 pixels per inch. A high-resolution image can then become a page measured in tens of inches. If you need a standard page, choose A4 or Letter instead.

Can I mix portrait and landscape images in one PDF?

Most converters apply one page size and orientation setting to the whole conversion. For mixed orientations, convert each group separately and combine the resulting PDFs with a merge tool.