JPG to PDF is one of the most common conversions there is: photograph a signed form with your phone, collect receipts for an expense claim, or turn a stack of scanned pages into the one file a portal will accept. The result is a PDF with one image per page, in the order you choose, that opens the same way on every device.
This guide covers how the conversion actually works, how to control page order and page size, what happens to image quality and file size, what to do with iPhone photos, how to do it with nothing but your phone's or computer's built-in tools, and the problems people run into most often. Where a number is given, it was measured.
How JPG to PDF conversion works
A PDF does not turn an image into text or shapes. It wraps it: each image becomes the picture on one page, and the PDF records how big that page is and where the picture sits on it. The two decisions that matter are the size of the page and whether the image is re-encoded on the way in.
In Filum's JPG to PDF tool, your browser first decodes each image with its orientation tag applied, so a photo your phone stored sideways comes out upright. Transparent areas are flattened onto white, because the page behind a picture in a PDF is white paper. Photos are then re-encoded as JPEG at a high quality setting (0.92 on a 0-to-1 scale), which changes the pixels slightly. PNG images stay PNG, which is lossless: every pixel is kept exactly, and a PNG with 256 or fewer colours is stored with a colour palette when that makes the file smaller. Images larger than 4,000 pixels on their longest side are scaled down to that size first, which is still far more detail than a printed A4 page can show.
Besides JPG and PNG, the tool accepts WebP, GIF, BMP and AVIF images, and HEIC photos in browsers that can decode them (more on that below).
Page size and orientation
Most converters put every image on a fixed paper size. On iLovePDF's free default, portrait A4, a landscape photo is shrunk to fit the width of the page and left with empty bands above and below it; Smallpdf adds margins around each image. Both were measured on 26 August 2026 with the same file.
Filum sizes each page to its image instead. A 4:3 landscape photo becomes a page of 842 by 631.5 points: the page is the photo, with no bands, no margins and no cropping. The longest side is capped at 842 points, the long edge of A4, so pages print at a sensible size, and a small image is never enlarged beyond its own resolution.
The consequence worth knowing: a PDF made from a mix of portrait and landscape photos has a mix of page shapes, exactly like the photos. On screen that is usually what you want. If a form or portal insists that every page be A4, open the finished PDF and print it to a new PDF with the paper size set to A4 and scaling set to fit; the print dialogs on Windows and macOS can both do that.
Converting several images into one PDF
Drop as many images on the page as you need, or pick them with the file picker. They appear in the order you added them, not sorted by name, and each one becomes one page in that order.
Reorder them before you create the PDF: every image has move up and move down buttons, and you can drag a row to a new position. The ✕ removes an image. The button tells you how many pages you are about to get, so you can check the count against what you expect before the file is made.
A file that cannot be used is not dropped silently. It stays in the list with a short reason beside it — “damaged image”, “PDF, not an image” or “needs Safari”, for example — and it is left out of the PDF. Remove it, or carry on and get a PDF of the rest.
There is no fixed limit on the number of images. The practical limit is your device's memory, because every image is decoded in the browser, so a large batch of full-resolution phone photos takes the longest.
Image quality and file size
Because photos are re-encoded, the PDF is not simply the photos added together. Measured on 21 September 2026: a 1600 by 1200 photo of 444,519 bytes became a one-page PDF of 425,323 bytes, slightly smaller than the photo it contains. Full-resolution phone photos are much larger than that, often several megabytes each, so a ten-photo PDF can easily pass an email attachment limit.
For graphics, screenshots and scans with few colours, PNG gives the smallest and sharpest result. On a 1600 by 1200 diagram with 256 colours, Filum's PDF was 114,019 bytes against iLovePDF's 115,142 — effectively a tie — and Smallpdf's 543,348, nearly five times larger, because it re-encoded the lossless image as JPEG. That comparison was measured on 26 August 2026 on one image; on a different image the order between Filum and iLovePDF could fall either way.
If the finished PDF is too large, run it through Compress PDF, which recompresses the images inside it. Or shrink the photos first with Resize Image: a photo about 2,000 pixels wide is plenty for reading on a screen, and far smaller than a full-resolution original.
iPhone photos (HEIC)
iPhones save photos as HEIC by default, and in practice only Safari can decode HEIC inside a browser. On Chrome, Edge or Firefox a HEIC photo is marked “needs Safari” and left out, rather than producing a blank page.
There are three ways round it. Open this page in Safari on your iPhone, iPad or Mac. Or get JPEG copies: with Settings, Photos, Transfer to Mac or PC set to Automatic, photos copied to a computer arrive as JPEG. Or change future photos with Settings, Camera, Formats, Most Compatible, which makes the camera save JPEG instead.
Doing it without an online tool
On Windows 10 and 11, select the images in File Explorer, right-click and choose Print (on Windows 11 it is under Show more options). Choose Microsoft Print to PDF as the printer, pick a layout such as Full page photo, and print; Windows asks where to save the PDF. The layouts fit each photo to a paper size, and Full page photo fills the page by cropping the edges of photos that are not the same shape as the paper.
On a Mac, select the images in Finder and open them together in Preview. Drag the thumbnails in the sidebar into the order you want, choose File then Print, and use the PDF menu in the print dialog to choose Save as PDF.
On an iPhone or iPad, the Files app can do it directly: select the images, tap the More button and choose Create PDF. From the Photos app, select the photos, choose Share then Print, pinch outwards on the preview to open it as a PDF, and share or save it from there. On Android, most gallery apps offer Print for a photo, and choosing Save as PDF as the printer produces a one-page PDF.
These built-in routes are fine for a few pages. Their limits are that the page size is always a paper size, the order is awkward to control on a phone, and some layouts crop or shrink the photo to fit.
No upload — everything in the browser
Filum's JPG to PDF tool runs entirely in your browser. The images are read from your device, decoded on a canvas and packaged into a PDF by a library running in the page. Nothing is sent to a server, and once the page has loaded the tool keeps working without a connection: on 21 September 2026 it converted a photo to a PDF with the network switched off.
That matters most for exactly the documents people photograph: passports, ID cards, medical letters, bank statements, signed contracts. The conversion is private because it happens on your own device, not because of a promise to delete the file afterwards.
Common problems
A photo comes out sideways. It should not: orientation tags are applied before the page is made. If it happens, the photo was captured sideways without a tag; turn the page afterwards with Rotate PDF.
A logo's background turned white. PNG transparency is flattened onto white, because PDF pages are white. That is expected, and it is the same on paper.
An image is marked “damaged image”. The file is truncated or is not really an image with that extension; export or download it again. “PDF, not an image” means the file is already a PDF — Merge PDF is the tool for joining PDFs together.