How to combine photos and scans into one PDF

Photographing receipts, scanning a signed contract page by page, assembling a portfolio, they all end the same way: a folder of images that somebody wants as one file. Four decisions determine whether the result is usable.

Decision 1: page size

A4 is 210 × 297 mm; US Letter is 8.5 × 11 inches (216 × 279 mm). They are close but not identical, so a Letter-sized PDF printed on A4 gets a slightly different margin. Pick the one your recipient uses. For documents, one image per page with the aspect ratio preserved is almost always right, stretching a photo to fill A4 distorts it.

Decision 2: DPI

DPI in this context means: how many of your image pixels land in one printed inch. It is arithmetic, not a setting you can wish for.

A modern phone photo is typically 4032 × 3024 pixels, which is more than enough for a 300 DPI A4 page. A screenshot from a laptop is often 1440 × 900, which fills an A4 page at only about 110 DPI, fine on screen, soft on paper. You cannot add detail that was never captured, so scan or photograph at the resolution you need from the start.

Decision 3: order

This is where most people lose ten minutes. Files named page1.jpg through page10.jpg sort as 1, 10, 2, 3 in almost every file browser, because the sort is alphabetical. Rename with zero padding, page01, page02 … page10, and everything falls into place automatically. Phone photos named IMG_0001 onwards are already padded and sort correctly by capture time.

Decision 4: file format

• JPEG, the right choice for photographs and camera scans. Already compressed, so the PDF stays small.
• PNG, right for screenshots, diagrams and anything with sharp text or flat colour. Lossless, so it produces a larger PDF; a full-page PNG screenshot can be several megabytes.
• HEIC, the iPhone default. Chrome and Firefox cannot decode HEIC, so a browser tool usually cannot read it directly. Two fixes: on the iPhone, Settings → Camera → Formats → Most Compatible makes the camera shoot JPEG from then on; or, for photos you already have, sharing them out of Photos to a Mac or Windows machine converts them to JPEG in transit.
• TIFF, common from office scanners and often multi-page. Convert to JPEG or PNG first; browser support is effectively nil.
• WebP and AVIF, decode fine in modern browsers, so they work if your tool supports them.

Doing it

1. Gather and renamePut every image in one folder and zero-pad the names so they sort in reading order.
2. Open the converterGo to the JPG to PDF tool and drop the whole folder in at once. Everything is processed in your browser, so a scanned passport or bank statement is never uploaded.
3. Check and fix the orderDrag any thumbnail that landed in the wrong place before generating the file.
4. Set page size and orientationA4 or Letter for documents. Choose auto-orientation so a landscape photo gets a landscape page instead of being shrunk to fit a portrait one.
5. Generate and checkOpen the PDF and page through it. Look for upside-down pages, which come from phone photos whose EXIF rotation was ignored.
6. Compress if it is going by emailTwenty phone photos make a 60 MB PDF. Run it through the compressor at 150 DPI first, see reducing a PDF for email.

Built-in alternatives

• macOS, select the images in Finder, right-click → Quick Actions → Create PDF. Selection order determines page order, so click them in sequence. Preview also lets you drag pages around afterwards in the sidebar.
• Windows, select the images, right-click → Print, choose Microsoft Print to PDF as the printer and Full page photo as the layout, then Print. Tick "Fit picture to frame" off if you do not want cropping.
• iPhone, in Photos, select the images → Share → Print, then pinch outwards on the print preview. It turns into a PDF you can share or save to Files. It is undiscoverable and it works.
• Android, Google Drive → + → Scan uses the camera, auto-crops, deskews and saves straight to a multi-page PDF.

Photographing documents well

• Shoot straight down, not at an angle. Perspective distortion is hard to fix and wrecks any later OCR.
• Use even, indirect light. Direct light creates a hotspot; a window on one side creates a gradient across the page.
• Put the page on a dark surface so the edge-detection in scanning apps can find it.
• Fill the frame with the page, and do not use digital zoom, move the phone closer instead.
• For anything you will need to search later, run OCR on the finished PDF. Details in how to OCR a scanned PDF.

Frequently asked questions