How the PDF is built
Each image becomes one page, in the order of the list. PNG files are read and their pixels written into the PDF with lossless compression, together with any transparency. The picture is then scaled to fill the printable part of the page (the page minus the margins) without cropping or stretching, and centered. "Fit to image" skips the paper sizes and makes each page the size of its picture, counting 96 pixels as one inch.
Scale = the smaller of (box width ÷ image width) and (box height ÷ image height)
Fit to image: page size in points = pixels × 0.75, plus the margin on each side
Worked example: a laptop screenshot on Letter paper
A full-screen laptop screenshot is 1920 × 1080 pixels. It is wider than tall, so with Auto orientation the Letter page turns landscape, 792 × 612 points. Small margins of 36 points leave a box of 720 × 540. Scale = the smaller of 720 ÷ 1920 = 0.375 and 540 ÷ 1080 = 0.5, so 0.375. The screenshot is placed at 720 × 405 points, 10 inches wide, which prints at 192 pixels per inch: small interface text stays readable on paper.
The same screenshot with Fit to image and no margin gives a page 1440 × 810 points (20 × 11.25 inches). That sounds large, but PDF viewers zoom it to fit your screen, and nothing is scaled down.
Good uses
- Proof for a dispute or claim. Screenshots of an order, a chat with support and a bank transaction, in date order, as one file an insurer or card issuer will accept.
- Steps for someone else. A sequence of screenshots showing how to change a setting, sent as one PDF instead of ten attachments.
- Graphics for print. Logos and diagrams exported as PNG, combined onto Letter pages with margins so nothing falls off the printer's edge.
Privacy
Screenshots often capture more than you meant to share, so this tool never sends them anywhere. The page loads once, then builds the PDF on your device. You can disconnect from the internet before adding your images and it still works.
Limits
Animated PNGs cannot be placed in a PDF, so only still images work. Every image is held in memory while the PDF is built: a laptop handles hundreds of screenshots, a phone fewer. For photos from a camera or phone, JPG to PDF does the same job and explains how phone photo rotation is handled. To turn a PDF back into PNG images, use PDF to PNG.
Questions people ask
Are my screenshots uploaded?
No. The PDF is put together in your browser, on your device, and saved to your Downloads. No image is sent to a server, which matters when the screenshots show account numbers, messages or medical results.
Will the PNG lose quality in the PDF?
No. PNG pixels are copied into the PDF losslessly, so text in a screenshot stays exactly as sharp as in the original file. The only change is technical: images with 16 bits per channel are stored at the usual 8 bits, which looks the same on screen and in print.
What happens to transparent areas?
Transparency is kept. The image goes into the PDF with its transparency layer, so see-through areas show whatever is behind them, which on a PDF page is plain white paper. A transparent logo on a white page looks just as it does in an image viewer with a white background.
Why is the PDF bigger than my PNG files?
Many PNGs save space by using a small palette of colors or shades of gray. A PDF stores the same picture as full color, so a palette PNG can grow two or three times larger inside the PDF, even though no pixel changes. If the PDF must fit an upload limit, run it through Compress PDF afterwards, or convert busy screenshots to JPG first.
Which page size is best for screenshots?
Choose "Fit to image" with no margin if the PDF is for reading on screen: each page is exactly the shape of its screenshot, with no white border. Choose Letter or A4 if it will be printed or attached to a form, so every page is a standard sheet.
Can I mix PNG, JPG and WebP files?
Yes. Add them in any mix and put them in order with the Up and Down buttons. JPGs are placed as they are, and WebP images are converted to high-quality JPG on the way in, because PDF files cannot hold WebP.