JPG to PDF: The Right Way to Convert Images to Documents

Converting images to PDF sounds like a trivial task until you actually try to do it well. The first time I needed to send a client a PDF of invoice scans, I used an online converter. The result? Some pages were landscape when they should’ve been portrait, the images were tiny and centered on giant A4 pages with massive white borders, and the file was 47MB for six pages.

There’s a right way and a wrong way to do this. Here’s what I’ve figured out.

When You Actually Need Image-to-PDF

Not every image needs to be a PDF. Here are the legitimate use cases where it genuinely makes sense:

Scanned documents — You scanned a contract, receipt, or form and got individual JPEGs. The recipient expects a single PDF file, not a zip of images.

Photo portfolios — Photographers and designers often need to send a curated collection as a single, paginated file that the client can flip through.

Evidence and documentation — Legal teams, insurance adjusters, and compliance officers need screenshots and photos compiled into a single document with a clear page order.

Meeting notes — Whiteboard photos from brainstorming sessions organized into a readable sequence.

Print preparation — When a print shop needs image files in PDF format with specific page sizes and margins.

If you just need to share photos, a zip file or shared album is usually better. PDF makes sense when page order, layout, and single-file delivery matter.

Page Size: Getting It Right

This is where most people go wrong. They leave the default setting and end up with A4 pages regardless of the image content.

A4 (210 x 297 mm)

The global standard for documents. Use this for scanned contracts, invoices, letters, and anything that might be printed on standard paper. If you’re in Europe, Asia, or most of the world, A4 is your default.

Letter (8.5 x 11 in / 215.9 x 279.4 mm)

The US and Canadian standard. Use this for documents intended for US audiences or US printers. It’s slightly wider and shorter than A4.

Fit to Image

This is the setting most people don’t know about but should use most often. It creates each page at the exact dimensions of its image with zero margins and zero wasted space. Perfect for photo portfolios, visual documentation, and any case where you don’t want white borders.

I’d estimate 70% of the time when someone converts images to PDF, “Fit to Image” is the correct choice. The other 30% is when the PDF will be printed on standard paper.

A3 (297 x 420 mm)

Double the size of A4. Use for architectural plans, large diagrams, poster designs, and detailed technical drawings where A4 doesn’t provide enough space.

Orientation: Auto Is Almost Always Best

Three options, one clear winner for most cases:

Auto (match image) — The PDF generator checks each image’s aspect ratio. Landscape images get landscape pages, portrait images get portrait pages. This is the right choice for mixed collections where some photos are horizontal and some are vertical.

Portrait — Forces all pages to portrait orientation. Use when all images are portrait or when you need a consistent page layout regardless of image orientation.

Landscape — Forces all pages to landscape. Use for presentation slides or screenshot collections that are all wider than tall.

My rule of thumb: if the images are all the same orientation, match it. If they’re mixed, use auto. I’ve never regretted using auto, but I’ve definitely regretted forcing portrait on a collection that included landscape shots.

Image Fit Modes Explained

This setting controls how the image is placed within the page area:

Contain (recommended for most uses)

The entire image fits within the page margins. If the image’s aspect ratio doesn’t match the page, you’ll see white space on two sides. No part of the image is cropped. This is the safest default because nothing gets cut off.

Cover

The image fills the entire page area. If the aspect ratio doesn’t match, the image is cropped to fit. Use this when you want full-bleed pages with no white space — like photo books or visual portfolios where the aesthetic matters more than showing every pixel.

Stretch

The image is deformed to exactly fill the page dimensions. People almost always look weird. Landscapes look weird. Everything looks weird. I’ve never found a legitimate use case for this in real-world work, but it exists if you need it.

Margins: Less Is Usually More

None — Zero margin, image extends to page edges. Best for portfolios, photo books, and “fit to image” page sizes.

Small (5mm) — Just enough breathing room to prevent edge-clipping when printing. Use when images will be printed on a standard printer that can’t print to the very edge.

Medium (10mm) — The safe default for printed documents. Matches most printer unprintable areas and looks professional for business documents.

Large (20mm) — Generous borders. Use for formal documents or when the images need to be framed by significant white space.

For digital-only PDFs that won’t be printed, I always use “None.” Margins exist to prevent content from being clipped by printers — if there’s no printer, there’s no reason for them.

Resolution and Quality

Here’s a detail that trips up a lot of people: the resolution of your source images directly determines the quality of the PDF. The PDF is just a container — it embeds the image data as-is. A blurry 640x480 JPEG won’t magically become sharp in a PDF.

For printable quality at standard paper sizes:

Paper Size	150 DPI (draft)	300 DPI (print quality)
A4	1240 x 1754 px	2480 x 3508 px
Letter	1275 x 1650 px	2550 x 3300 px
A3	1754 x 2480 px	3508 x 4960 px

If your source images are smaller than these dimensions, they’ll look fine on screen but may appear soft when printed. Smartphone photos at 12MP+ generally exceed even 300 DPI A4 requirements, so this is mainly a concern for screenshots and web-downloaded images.

Page Order Matters

This sounds obvious, but I can’t count the number of multi-page PDFs I’ve received where the pages were in random order. When you have multiple images:

Name your files sequentially before adding them (001-cover.jpg, 002-intro.jpg, etc.)
Verify the order after adding — drag to reorder if needed
Think about the reader’s experience — title/cover page first, supporting material after

The Image to PDF Converter lets you drag cards to reorder pages before generating. Take 10 seconds to verify the order. It makes a professional difference.

File Size Optimization

A common complaint: “My PDF is 200MB for 30 pages.” This happens because the source images are high-resolution RAW-adjacent files that weren’t optimized beforehand.

My pre-processing checklist:

Resize to the dimensions you need — a 6000x4000 photo destined for an A4 PDF only needs to be about 2480x1654 at 300 DPI. Everything beyond that is wasted data. Use the Image Resizer to scale down.
Use JPEG, not PNG — For photographs, JPEG at quality 85 is typically 5-10x smaller than PNG with no visible difference.
Compress beforehand — Run images through the Image Compressor at quality 80-85 before converting to PDF.

A 30-page PDF of properly sized and compressed photographs should be 5-15MB, not 200MB.

A Real Workflow

Here’s what I did last week when a contractor sent me photos of a renovation project and needed them compiled into a single PDF for the building inspector:

Received 18 JPEG photos from the contractor (mix of portrait and landscape)
Opened the Image to PDF Converter
Dropped all 18 photos in
Rearranged to logical order: exterior shots first, then room-by-room, then detail shots
Settings: A4, Auto orientation, Contain fit, Medium margin
Set PDF title to “Renovation Progress Report — March 2026”
Generated — 18-page PDF, 8.2MB
Emailed directly to the inspector

Took about two minutes. The contractor was impressed enough to ask how I did it.

Convert images to PDF: The Image to PDF Converter supports multiple images, drag-to-reorder, all standard page sizes, auto-orientation, and custom margins. Everything happens in your browser — your photos aren’t uploaded anywhere.