TidyToolsWhy the file you get back is usually worse than it needs to be
Most free "JPG to PDF" services re-encode your images on the way through. They have a good reason — it makes their bandwidth bill smaller — but you pay for it in a document where the small print on a scanned form has gone soft, which is exactly the text somebody needs to read.
There's no bandwidth bill here, because nothing is transmitted. What happens to each image depends on what a PDF is able to store:
- JPG goes in untouched. PDF can hold a JPEG stream directly, so your file is placed inside the document byte for byte. It is never decoded, so it cannot lose anything — the page is exactly as sharp as the photo you took.
- PNG is repacked, losslessly. PDF can't store a PNG as a PNG, so the image is unpacked and stored in the format PDF does understand. It's lossless in both directions: every pixel, and any transparency, comes out identical. Nothing is thrown away, and the result is usually smaller than the PNG was.
- WebP, GIF and BMP have to be converted, since PDF can't carry them in any form. Those become high-quality JPEGs, and the row for that image says so rather than leaving you to guess.
The distinction that matters is the one the upload-first services blur: none of this is lossy re-compression. Nothing here takes a photo, decodes it, and squeezes it back down to save space at your expense.
A worked example
A rental agency wants your signed tenancy agreement back as a single PDF. You photograph all four pages on your phone. They arrive named IMG_4471 through IMG_4474, and one of them is upside down in the list because you took it last and dropped it in first.
Drop all four in, use the arrows to put them in reading order, leave the size on A4 with a 10 mm margin, and press Make PDF. Each photo is fitted to its own A4 page — landscape shots get a landscape page automatically — and you get a four-page document that looks like a scan rather than a camera roll.
Choosing a page size
- A4 or Letter — every image is fitted onto a standard page, centred, with the margin you pick. Orientation is chosen per image, so a landscape photo doesn't end up shrunk into a portrait page with waste above and below. This is what you want for anything being submitted, printed or filed.
- Match image — each page takes the exact proportions of its image, sized to print at 150 dpi. Nothing is letterboxed and there are no margins. Use it for a photo book, a set of screenshots, or anything where a white border would be wrong.
Why your PDF is suddenly 40 MB
A PDF made of photographs is roughly as big as the photographs were, because that's what's inside it. Twelve-megapixel phone images run 3 to 6 MB each, so ten pages is comfortably past most upload limits, and no PDF setting will change that — the size is in the pixels.
The fix is to deal with it before the images become a document: run them through the image compressor with a target size first, then build the PDF from the smaller copies. Shrinking a 4000-pixel-wide photo of an A4 page to around 1700 pixels loses nothing a reader will notice — the text is still far sharper than a real scanner would produce — and cuts the file by most of its bulk.
iPhone photos
Photos straight off an iPhone are usually HEIC, and Chrome, Edge and Firefox can't decode that format at all — the decoder is patent-encumbered and Apple's is the one your phone uses. Run them through the HEIC to JPG converter first and then bring the JPGs here. If you'd rather skip the step, set your iPhone to Settings → Camera → Formats → Most Compatible and it will shoot JPG from then on.
Frequently asked questions
Are my images uploaded anywhere?
No. The PDF is assembled in your browser and saved straight to your downloads. There is no server, no account and nothing stored. Load the page, disconnect from the internet, and it still works.
Does it re-compress my photos?
Never in a way that loses quality. A JPG is placed into the PDF byte for byte and is never decoded at all. A PNG can't be stored as a PNG inside a PDF, so it's unpacked and repacked in a format PDF understands — lossless both ways, every pixel and any transparency identical, and usually a smaller result than the PNG. Only WebP, GIF and BMP are genuinely converted, to high-quality JPEG, and the row for that image tells you.
Can I use HEIC photos from my iPhone?
Not directly, because desktop browsers can't decode HEIC. Convert them with the HEIC to JPG converter first, or switch your iPhone to "Most Compatible" in the camera settings so it shoots JPG.
Why is my PDF so large?
Because photographs are large, and a PDF of photographs contains them. Compress the images to a target size first and then build the document — that's the only thing that meaningfully reduces it.
Can I change the order of the pages?
Yes. The arrows on each row move an image up or down, and the number on the left is the page it will become. Drop files in any order and sort them afterwards.
Will landscape photos be rotated or squashed?
Neither. On A4 or Letter each page takes the orientation of its own image, and the picture is scaled to fit while keeping its proportions. Nothing is stretched or cropped.
Is there a limit on how many images, or a watermark?
Neither. Add as many as you like and nothing is stamped onto the result. There's no sign-up and no paid tier.
How do I combine this with an existing PDF?
Make the PDF here, then join the two with the PDF merger — also entirely in your browser.