How to Combine JPG to PDF (Without Uploading Your Files)

• 2 min read

How to Combine JPG to PDF (Without Uploading Your Files)

Turning a stack of photos into one PDF is one of those tasks that sounds trivial until you try it. Every result on the first page of Google asks you to upload your images to their server first. For a holiday album that is fine. For a passport scan, a signed contract, or a medical form, it is not.

This guide covers the whole job — ordering, page size, orientation, transparency, and file size — and does it with a converter that never sends your images anywhere. Tools used: /jpg-to-pdf for the merge, /compress if the images are oversized, and /compress-pdf if the finished PDF is.

The Short Version

  1. Open /jpg-to-pdf
  2. Paste (Ctrl+V / ⌘+V), drop, or pick your images — JPG, PNG, WebP, GIF and BMP all work
  3. Drag the thumbnails into the order you want
  4. Pick a page size: Fit (page matches each image) or A4 / Letter
  5. Click build, then download

Everything after step 1 happens inside your browser tab. Open DevTools → Network before you start and you will see no outbound request carrying your images. That is the part you can verify yourself rather than take on faith.

Step 1: Get Your Images In

Three ways in, and they all behave the same:

  • Paste — Ctrl+V (Windows) or ⌘+V (Mac). Useful when the image is already on your clipboard from a screenshot.
  • Drag and drop — drop a multi-file selection straight onto the page.
  • File picker — click and select. Hold Shift or Ctrl/⌘ to multi-select.

Mixed formats in one document are fine. JPG and PNG are embedded directly; WebP, GIF and BMP are converted to PNG in the browser first, because the PDF format itself has no native slot for them.

Step 2: Fix the Order Before You Build

This is the step people skip and then redo. File pickers return files in whatever order the operating system feels like — usually alphabetical, which puts IMG_10.jpg before IMG_2.jpg. Drag the thumbnails into the sequence you actually want before building.

If you are scanning a multi-page document with a phone, name the files 01, 02, 03 rather than 1, 2, 3. Zero-padding makes alphabetical order match page order, and you can skip the dragging entirely.

Step 3: Choose the Page Size — This Matters More Than It Sounds

There are two genuinely different modes here, and picking the wrong one is the most common cause of a PDF that "looks weird":

Mode What happens Use it when
Fit Each page is built to match its image exactly. No borders, no letterboxing. Photo albums, screenshots, anything screen-only
A4 / Letter Each image is scaled to fit a standard sheet and centred, with whitespace around it Anything that will be printed, emailed to an office, or submitted to a form

If the document is going to a printer or an institution, pick A4 or Letter. A "Fit" PDF made from phone photos produces pages at odd dimensions, and print shops handle those unpredictably.

Step 4: Orientation and Mixed Portrait/Landscape Sets

Orientation has three settings, and Auto is the one that solves the problem most guides do not mention.

  • Auto decides per image: a wider-than-tall image gets a landscape page, a taller-than-wide image gets a portrait page. A mixed set comes out with each photo upright on its own correctly-shaped page.
  • Portrait or Landscape forces every page the same way. A landscape photo on a forced-portrait A4 page is scaled down to fit the width, leaving large empty bands above and below.

So: mixed photo sets → Auto. A document that must be uniformly portrait (most official forms) → Portrait, and accept the banding on any sideways image.

Margins are separate: None, Small, or Large. None is right for photo albums. Small or Large is right if the pages will be printed and possibly hole-punched or bound.

Step 5: What Happens to Transparent PNGs

A real gotcha that no tool page explains. If you feed in a PNG with a transparent background — a logo, a cut-out product shot — the transparency is preserved in the PDF. It does not turn black.

What it looks like depends on what is behind it. A PDF page is white, so a transparent area shows as white when you view or print it. But it is genuinely transparent, not filled: if the PDF is later placed onto a coloured background in a design tool, the colour shows through.

If you specifically need a solid white background baked in, run the image through /compress and export as JPG first — JPG has no alpha channel, so the transparency gets flattened to white on the way out.

Step 6: Controlling File Size

Merged PDFs get large fast, because each image goes in at full resolution. A dozen 12-megapixel phone photos will produce a PDF well over 30 MB, which most email systems will reject.

Compress in the right order. This is the part that trips people up:

  1. Shrink the images first, then merge. Run them through /compress — resize to something sensible (1600 px on the long side is plenty for anything screen-viewed, 2400 px if it will be printed) and export at quality 80. Then build the PDF.
  2. Only compress the finished PDF as a fallback. /compress-pdf works, but it is recompressing images that have already been encoded once. Two lossy passes look worse than one.

A rough guide to what to aim for:

Purpose Long edge Expected PDF size (10 pages)
Email attachment 1200 px 1–3 MB
Screen reading / archive 1600 px 3–6 MB
Printing at A4 2400 px 8–15 MB

Doing It on Windows, Mac, and iPhone

You do not need any of these — the browser method above works identically on all three — but for completeness:

Windows. Select your images in File Explorer, right-click, Print, and choose "Microsoft Print to PDF". It works, but it forces a fixed page size and offers no reordering beyond file name.

Mac. Select the images in Finder, right-click, Quick Actions → Create PDF. Fast, but it uses Finder's current sort order and gives you no page size control at all.

iPhone. In Photos, select images, Share, Print, then pinch outward on the print preview to turn it into a PDF, and share that. It is a genuinely obscure gesture and it produces a fixed Letter-sized document.

All three are fine for casual use. Where they fall down is control: none lets you set page size, orientation, and margins independently, and none lets you reorder pages without renaming files first.

Why "No Upload" Is Not Just Marketing

Every mainstream JPG-to-PDF converter is a server-side service. You upload, they process, you download. Their privacy policies typically promise deletion after some window — an hour, a day — and you are trusting that promise.

The browser-local approach removes the question entirely. The conversion runs in JavaScript and WebAssembly inside your own tab, using pdf-lib to assemble the document. Nothing to delete, because nothing was ever sent.

You can confirm this in about ten seconds:

  1. Open /jpg-to-pdf
  2. Press F12 to open DevTools, go to the Network tab
  3. Add an image and build the PDF
  4. Watch the request list — you will see the page's own assets load, and nothing carrying your image

For a holiday photo, none of this matters. For a passport page, a signed contract, a bank statement, or a medical record, it is the whole point.

Common Problems

The pages are out of order. The file picker sorted them alphabetically. Reorder the thumbnails before building, or rename with zero-padded numbers.

One image is sideways. Some cameras record orientation as EXIF metadata rather than rotating the pixels. Fix the rotation before converting — and note that stripping EXIF with /exif can remove the orientation flag, which makes the problem visible rather than fixing it.

The PDF is enormous. You merged full-resolution originals. Resize first (Step 6), then rebuild.

A PNG looks like it has a white box around it. That is not a box — it is the transparent region showing the white page. See Step 5.

HEIC photos from an iPhone will not load. Most browsers cannot decode HEIC. Convert them with /heic-to-jpg first, then merge the JPGs.

The TL;DR

  1. Open /jpg-to-pdf and add your images
  2. Reorder before building — the file picker's order is rarely the one you want
  3. Fit for screen, A4/Letter for print
  4. Auto orientation for mixed portrait/landscape sets
  5. Resize images before merging, not the PDF afterwards
  6. Nothing uploads — check the Network tab if you want proof

The whole thing takes under a minute, and your files never leave your device.