How to Convert Images to PDF (JPG, PNG, HEIC)

You've got a stack of photos — receipts, signed forms, whiteboard notes, whatever — and someone needs them as a PDF. Maybe it's your landlord wanting a scanned lease. Maybe HR wants your ID as a single document. Maybe you just photographed ten pages of notes and need to email them without attaching ten separate files.

Whatever the reason, converting images to PDF is one of those tasks that sounds like it should take five seconds. And honestly, it should. But if you've tried it recently, you've probably run into the usual mess: apps that want a subscription, websites that slap watermarks on everything, or tools that quietly compress your images into blurry garbage.

Let's fix that. Here's how to actually convert JPG, PNG, and HEIC images to PDF — quickly, free, and without losing quality.

Why Convert Images to PDF in the First Place?

Before we get into the how, it's worth thinking about the why. PDFs aren't just "another file format." They solve real problems that image files don't:

Universal compatibility. A PDF looks the same on every device, every operating system, every screen. A JPG? Depending on the viewer, you might get different color rendering, rotation issues, or scaling weirdness.

Multiple pages in one file. This is the big one. Nobody wants to receive 15 separate image attachments. A single PDF keeps everything together, in order, paginated properly.

Smaller file sizes. A well-made PDF with embedded images is often smaller than the raw image files combined. This matters when you're emailing documents or uploading to portals with size limits.

Professional appearance. Sending a JPG of a signed contract feels... informal. The same document as a PDF feels like an actual document. Perception matters.

Method 1: Convert Images to PDF Online (Fastest)

The fastest way to turn images into a PDF is with an online converter. No software to install, works on any device with a browser.

With OnlyDocs, here's the process:

1. Go to onlydocs.net and open the PDF editor
2. Create a new blank document or start from an existing PDF
3. Insert your images — drag and drop works
4. Arrange the pages however you want
5. Export as PDF

That's it. No account required for basic conversions, no watermarks, no file size tricks. The images stay at their original resolution unless you choose to compress them.

This approach works well when you need to combine multiple images into one PDF. You can reorder pages, rotate images that came out sideways (looking at you, phone camera), and even add text or annotations before exporting.

Method 2: Use Your Phone's Built-In Tools

Here's something most people don't know: your phone can already do this without any app.

On iPhone (iOS)

iPhones save photos as HEIC by default (Apple's High Efficiency Image Format). That's great for storage, but annoying when someone asks for a PDF. Here's how to convert:

1. Open the Photos app and select the image(s) you want to convert
2. Tap the Share button (the little square with an arrow)
3. Select "Print" — yes, Print
4. On the print preview screen, pinch outward with two fingers on the preview image
5. This opens the image as a PDF. Tap Share again to save or send it

This trick works because iOS generates a PDF behind the scenes for print preview. It handles HEIC, JPG, PNG, and pretty much any image format iOS can display. The quality stays intact because it's not re-compressing anything.

For multiple images, select all of them before hitting Share. They'll end up as separate pages in one PDF.

On Android

Android doesn't have quite as elegant a built-in trick, but it's still doable:

1. Open the image in Google Photos or your gallery app
2. Tap the three-dot menu and select "Print"
3. Change the printer to "Save as PDF"
4. Hit the download/save button

Same idea as iPhone — the print dialog generates a PDF. Works with JPG, PNG, and most formats Android supports. HEIC support depends on your Android version, but anything from Android 10 onward handles it fine.

Method 3: Convert on Desktop (Mac and Windows)

On Mac

macOS has a surprisingly good built-in PDF workflow:

1. Open the image(s) in Preview (it's the default image viewer)
2. If you need multiple images, select them all in Finder, right-click, and choose "Open With > Preview"
3. In Preview's sidebar, arrange the pages in the order you want
4. Go to File > Export as PDF

Preview maintains image quality and handles all common formats including HEIC (since macOS natively supports it). You can also adjust page size and orientation before exporting.

On Windows

Windows doesn't have a single built-in tool that handles this gracefully, but the Print to PDF option works:

1. Open the image in Photos or any viewer
2. Press Ctrl+P to print
3. Select "Microsoft Print to PDF" as the printer
4. Choose your paper size and orientation
5. Click Print and choose where to save the PDF

For multiple images, select them all in File Explorer, right-click, and select "Print." Windows will combine them into one print job. The catch: Windows sometimes reorders the images alphabetically, so check the preview before saving.

Dealing with HEIC Files Specifically

HEIC (also called HEIF) is Apple's default photo format since iOS 11, released back in 2017. It's about 50% smaller than JPG at the same quality, which is why Apple uses it. But outside the Apple ecosystem, it can be a headache.

Most online converters now handle HEIC natively. OnlyDocs accepts HEIC uploads directly — no need to convert to JPG first as a middle step.

If you're stuck on a system that won't open HEIC files, the quickest workaround is changing your iPhone's camera settings: go to Settings > Camera > Formats > Most Compatible. This switches to JPG. You lose the storage benefits of HEIC, but compatibility headaches disappear.

Image Quality: What Actually Happens During Conversion

One thing people worry about is quality loss. Here's the truth: converting an image to PDF doesn't inherently reduce quality. A PDF is essentially a container — it wraps your image in a document format without re-encoding it.

The quality problems happen when a tool decides to re-compress your images during conversion. Some online converters do this to keep file sizes small (and their servers happy). You end up with a PDF where the images look like they were taken with a potato.

Signs of quality loss to watch for:

• Visible compression artifacts (blocky patches, especially in gradients)
• Text in images becoming harder to read
• File size dramatically smaller than the original images combined
• Colors looking washed out or shifted

A good converter gives you control over this. You should be able to choose between "keep original quality" and "compress for smaller size." If a tool doesn't give you that choice, it's probably compressing behind your back.

Combining Multiple Images into One PDF

The most common use case isn't converting a single image — it's combining a bunch of them. Scanned documents, receipt photos, slides from a presentation, pages from a book.

Here's the workflow I'd recommend:

1. Get all your images into one folder
2. Name them in the order you want (01-cover.jpg, 02-page1.jpg, etc.) — this saves rearranging later
3. Upload the batch to OnlyDocs
4. Check the order, rotate any sideways images
5. Export as a single PDF

If you're doing this regularly — say, you scan a lot of documents for work — it's worth building a habit around file naming. Future you will appreciate not having to figure out which IMG_4582.jpg comes before IMG_4583.jpg.

Frequently Asked Questions

Does converting JPG to PDF reduce image quality?

Not if the tool does it right. A properly made PDF embeds the original image data without re-compressing it. The file size might even be nearly identical. The only time quality drops is when a converter re-compresses your images during the process — avoid tools that don't give you quality settings.

Can I convert HEIC to PDF without converting to JPG first?

Yes. Modern tools handle HEIC directly. On a Mac, Preview opens HEIC natively. Online, OnlyDocs and most current converters accept HEIC uploads without an intermediate conversion step.

What's the maximum number of images I can combine into one PDF?

There's no hard technical limit on the PDF format itself — people have made PDFs with thousands of pages. Practically, most online tools cap at somewhere between 50 and 200 images per batch. If you need more than that, a desktop tool like Preview on Mac will handle it without restrictions.

How do I keep the PDF file size small when combining lots of images?

Start with reasonably sized images. A 12-megapixel phone photo at full resolution is overkill for a document scan. Most tools offer a compression option during export — medium compression typically cuts file size by 40-60% with minimal visible quality loss. For text-heavy scans, higher compression works fine since text stays readable even at lower quality.

Wrapping Up

Converting images to PDF is one of those things that should be boring. And with the right tool, it is. No subscriptions, no watermarks, no mysterious quality loss.

For one-off conversions, your phone's built-in print trick works fine. For combining multiple images, reordering pages, or working with HEIC files, OnlyDocs handles it in your browser without any fuss.

Got a stack of photos that need to become a document? Go turn them into a PDF. It'll take less time than it took to read this article.