Turn Photos into a PDF Without Uploading Them
Combining photos into a single PDF is one of the commonest document tasks there is — an ID submitted to a portal, receipts for an expense claim, a signed page photographed and sent back. Doing it locally is straightforward, but four specific problems account for almost every failure: the iPhone's default file format, rotation tags, file size, and photographing instead of scanning.
The HEIC problem on iPhone
Since iOS 11, iPhones save photos in HEIC by default — a more efficient format that stores the same image in roughly half the space of JPEG. The catch is that most browsers cannot decode HEIC. If you select a photo and the tool appears to do nothing, or throws an error, this is almost always the cause.
Three ways to fix it:
- Change the default. Settings → Camera → Formats → Most Compatible. New photos are then saved as JPEG and the problem stops recurring.
- Convert on export. In the Photos app, share the photo and choose Copy as JPEG, or email it to yourself — the attachment arrives as JPEG.
- Screenshot it. A screenshot is always PNG. It also loses resolution, so it is the last resort for a document that must be legible.
Why photos arrive sideways
When you turn a phone to take a landscape photo, the sensor still records the image in its own orientation. The phone writes an EXIF orientation tag into the file — a note saying "display this rotated 90 degrees". Your gallery reads that tag and shows it upright. The pixels themselves were never changed.
The problem comes when a tool re-encodes the image: if it copies the pixels without applying the tag, the photo appears rotated in the PDF. Some pipelines handle this correctly and some do not, which is why the same photo can work on one site and come out sideways on another.
The reliable fix is to bake the rotation into the file before converting. Open the photo in any editor, rotate it to where you want it, and save — most editors then write upright pixels and reset the tag. Alternatively, use the tool's own rotate control if it offers one, and check page one of the output before converting the rest.
Keeping the file size sane
This is where image PDFs get out of hand. A single modern phone photo is typically 3 to 6 MB, and the arithmetic is unforgiving:
| Photos | Typical PDF size | Consequence |
|---|---|---|
| 3 | 10–18 MB | Fine for most portals |
| 10 | 35–60 MB | Above the email attachment limit of most providers |
| 30 (a full expense claim) | 100–180 MB | Will be rejected by almost every upload form |
A PDF page does not need a 4000-pixel image to look sharp. For on-screen reading roughly 2000 pixels across is plenty; for print, about 2500. Reducing the photo's longest edge to around 2000 pixels before combining typically cuts the file to a fifth with no visible loss at reading size.
If you have already produced the PDF, compress it afterwards — see how to compress a PDF without uploading it, which explains why image PDFs shrink so much better than text ones.
Combine images locally in the browser
Our PDF toolbox takes multiple images and places each on its own A4 page, scaled to fit and centred. Everything is done in the tab; no image is uploaded.
- Open the toolbox and choose Images → PDF.
- Select or drag the images. The order in which they are listed becomes the page order.
- Reorder with the arrows if needed — getting this right before converting is easier than fixing it afterwards.
- Convert and save. Check page one, a middle page and the last page.
Because the images are placed at their own resolution rather than resampled, the file size is close to the sum of the input images. That is honest behaviour but it means a large batch produces a large PDF; reduce the images first if the result has to be emailed.
On the phone itself
iPhone
Open Files, tap … → Select, tick the images, then … → Create PDF. The result stays on the device. For a handful of photos this is faster than any website.
Android
There is no system-wide equivalent. Use the browser with a local-processing tool, or a gallery app with a "print to PDF" option, which routes through the Android print framework and produces a PDF on the device.
Photograph or scan?
A photograph of a document is not the same thing as a scan, and for anything a third party will read the difference matters:
| Photograph | Scan (scanner app or flatbed) | |
|---|---|---|
| Perspective | Distorted unless perfectly square to the paper | Flattened |
| Lighting | Uneven; shadows from your hand or the page curl | Evenly lit |
| Background | Desk, floor, hand — all included | Removed or white |
| Legibility when printed | Variable | Consistent |
| File size for the same legibility | Larger | Smaller |
If the document is an ID, a certificate or anything that will be checked by a human, use a scanner app that flattens the perspective, or a flatbed scanner. If it is a receipt for your own records, a photo is fine.
Checklist before you submit it
- Page order — page 1 is what you think it is, and the last page is the last.
- Orientation — nothing sideways. This is the most common defect.
- Nothing cut off — the whole page is in frame, all four corners visible.
- Legible at 100% — zoom in and read the smallest text that matters.
- File size — under the limit of the portal you are uploading to, which is often 5 or 10 MB.
- No unintended content — a desk, a reflection, a document underneath.
Questions we get asked
Can I combine JPG and PNG in one PDF?
Yes. Both are decoded by the browser and each becomes a page. PNG keeps transparency, which means a transparent background may appear as white or black depending on the converter — check the output if you are placing a logo on a page.
What resolution should I use for a document that will be printed?
Around 2500 pixels on the long edge for an A4 page is a reasonable target — that is roughly 300 dots per inch across the width. Below about 1200 pixels the text starts to look soft when printed.
Can I put two photos on one page?
Not with a simple image-to-PDF tool, which places one image per page. If you need a grid layout, assemble the composite in an image editor first and use that single image as the page.
Is it safe to make a passport photo into a PDF on a website?
Only with a tool that processes locally. Confirm it by loading the page, disconnecting from the internet, and converting — if it still works, the image was never sent. A passport scan is one of the documents most worth keeping off other people's servers.
Why does the PDF look blurry when I zoom in?
Because the image inside it has a fixed resolution. A PDF does not add detail that was not in the source. If the source was a screenshot or a messaging-app copy, the resolution is already reduced; use the original file from the camera roll instead.