Images to PDF

The two page-size modes, in real numbers

Fit to A4 builds every page at 595.28 by 841.89 points, which is the exact equivalent of 210 by 297 mm. A margin of 36 points, half an inch, is left on all four sides, so each picture is placed inside a box of 523.28 by 769.89 points and centred both ways.

The scaling is proportional and capped at 1, meaning an image is never enlarged. A small screenshot stays its natural size in the middle of a white page rather than being blown up into a soft mess. Larger pictures shrink to fit whichever dimension runs out first.

Match each image's size skips all of that and makes the page exactly the dimensions of the picture, with the picture filling it edge to edge. No margins, no white space, no scaling.

Which to pick comes down to what happens next. Anything that will be printed, emailed to an office, or attached to an application form should be A4, because uniform pages behave predictably in a printer tray. Anything that is really a set of screenshots or artwork to be read on screen usually looks better matched to its own size, with no borders.

Why matched sizes can produce an enormous page

This mode has a quirk that catches people out, and it is worth understanding rather than working around blindly.

PDF measures in points, 72 to the inch, and this mode maps one image pixel to one point. So a photo from a modern phone at 4032 by 3024 pixels becomes a page 4032 by 3024 points, which is 56 by 42 inches, or about 1420 by 1070 mm. Your reader will open it zoomed out to a fraction of full size, and a print dialog will offer to scale it down to fit A4.

Nothing is broken and no quality is lost. The image data is identical either way. But if someone prints that page at its stated size on a plotter they will get a poster. For photos and scans, A4 mode is almost always the one you want, and the matched mode really suits screenshots, which at typical dimensions such as 1920 by 1080 pixels give a page about 27 by 15 inches.

Two things the tool does not do

It does not rotate anything. Phone cameras often record a photo in the sensor's native orientation and store a separate tag saying which way up it should be shown. Your gallery reads that tag; this conversion does not. A photo that looks upright on your phone can land sideways in the PDF. The fix is to open the image, rotate it and save it so the pixels themselves are the right way up, or fix the finished document with Rotate PDF.

It also does not re-compress. JPEGs are embedded exactly as they are, so a folder of twelve photos at 3 MB each produces a PDF of roughly 36 MB. PNGs are stored with lossless compression, which is fine for screenshots and diagrams but wasteful for photographs: a photo saved as PNG can occupy five or ten times what the same picture would as a JPEG. If the finished PDF is too big to send, shrink the images first with Compress Image to KB, then rebuild it.

A worked example

You photograph six pages of a handwritten form, each about 2.4 MB as a JPEG at 3024 by 4032 pixels. Add all six, use the arrows to correct the two that imported out of sequence, choose Fit to A4, and name the output form-signed.pdf.

Each photo is taller than it is wide, so the height is the limiting dimension: it scales to 769.89 points tall and about 577 points wide, and is centred with roughly 9 points of extra white on each side beyond the margin. The result is a 6 page A4 document of around 14 MB that prints cleanly on any printer. The effective resolution works out near 280 DPI across the page, which is plenty for handwriting to stay legible.

Format support

JPG and PNG only. That covers almost every photo, screenshot and scan in circulation, but there are notable gaps. Photos straight off an iPhone are often HEIC, WebP is common from web downloads, and scanners sometimes produce TIFF. None of those can be embedded, and a file that slips past the name check produces a named error telling you which one failed rather than silently dropping it. Run them through Image Converter first.

Animated GIFs are not supported either. Everything runs in your browser, so your files never leave your device, and you will see a warning once your selection passes 100 MB in total because the whole job is assembled in memory.

Questions

Can I put two images on one page?

No, this always places one picture per page. Combining images side by side needs an image editor before you convert.

Will the text in my scanned pages be searchable?

No. A photograph of writing is a grid of pixels with no character data, so the PDF has nothing to search. That is true of any image-based PDF, however it was made.

What order do the images come out in?

Exactly the order shown in the list, top to bottom. Files often import in whatever order the browser hands them over, which is not always alphabetical, so check the list before creating the document.

Can I add more images to a PDF I already made?

Not directly. Build a second PDF from the new pictures and join the two with Merge PDF.

Why does my one-page PDF look like it has a border?

That is the half-inch margin in A4 mode, plus extra white on the axis that did not limit the fit. Switch to matched size if you want the picture running right to the page edge.