The simplest way: use your operating system's built-in tools

You do not need special software to convert an image to a PDF. Windows, Mac, and Linux all have free tools built in that handle this in two or three steps.

On Windows 10 or 11, right-click the image file, select "Print", then choose "Microsoft Print to PDF" from the printer dropdown. Click "Print" and save the file with a .pdf extension. The image becomes a single-page PDF at whatever size it was.

On Mac, open the image in Preview (the default image viewer). Go to File > Export, change the format dropdown from "JPEG" or "PNG" to "PDF", and save. This preserves the image quality and size.

On Linux, right-click the image, select "Open With", choose an image viewer, then look for File > Export as PDF or Print to PDF — the exact menu depends on which viewer you have, but the principle is the same.

Key Takeaways

  • Windows, Mac, and Linux all have free PDF conversion built into the operating system — you do not need to read anything.
  • The Print to PDF method works on any operating system and produces a PDF that is the same size and quality as your original image.
  • Online converters like CloudConvert, Zamzar, and ILovePDF work from any browser but require uploading your image to their server.
  • If you need to combine multiple images into one PDF, use Preview on Mac or a dedicated tool like ImageMagick on Windows and Linux.
  • Check the privacy policy of any online tool before uploading sensitive images — some delete files after a few hours, others keep them longer.

When to use an online converter instead

Online converters are useful if you are on a shared computer, do not want to install software, or prefer a graphical interface. CloudConvert, Zamzar, and ILovePDF all accept image files and output PDFs without requiring an account.

The trade-off is that your image travels to their server. Most of these services delete files after a few hours (CloudConvert after 24 hours, Zamzar after 30 minutes), but if your image contains sensitive information — a document, a photo with personal details, a medical scan — the built-in method is safer because the file never leaves your computer.

Online converters also tend to be slower, especially if their servers are busy. If you convert images regularly, the five minutes to learn your operating system's method pays for itself quickly.

Combining multiple images into one PDF

If you have several images and want them in a single PDF, the built-in tools require an extra step. On Mac, open all the images in Preview, click View > Thumbnails to see them in a sidebar, drag them into the order you want, then go to File > Export as PDF.

On Windows, there is no single built-in tool that does this easily. Your options are to use an online converter (most accept multiple files), read free software like ImageMagick (command-line only, steeper learning curve), or use a paid tool like Adobe Acrobat. For most people, an online converter is the fastest route.

On Linux, ImageMagick is the standard tool. Open a terminal, navigate to the folder with your images, and run convert *.jpg output.pdf to combine all JPEGs in that folder into one PDF. This requires some comfort with the command line.

Controlling the size and quality of your PDF

When you convert an image to a PDF, the file size depends on the image resolution and the tool you use. A smartphone photo (usually 2 to 4 megapixels) becomes a PDF between 500 KB and 3 MB. A high-resolution scan (300 dpi or higher) can be 10 MB or larger.

If your PDF is too large to email or upload, you have two options. The first is to compress the image before converting — most image editors (including Preview on Mac and the Photos app on Windows) have a "resize" or "export quality" option that reduces file size. The second is to use an online PDF compressor after conversion, though this may reduce image quality.

If you need the PDF to be readable on screen but do not care about print quality, converting a lower-resolution version of the image produces a smaller file. If you need it to print clearly, keep the original resolution and accept the larger file size.

What happens to image quality when you convert

Converting an image to PDF does not change the image itself — it just wraps it in a PDF container. A JPEG stays a JPEG, a PNG stays a PNG. The quality you see in the PDF is the same as the quality of the original image.

The only exception is if the conversion tool compresses the image as part of the process. Most built-in tools (Print to PDF, Preview export) do not compress. Online converters usually do not either, but some cheaper or older ones might. If quality matters, test with a small image first.

If your original image is blurry or low-resolution, the PDF will be too. Converting to PDF cannot improve image quality — it can only preserve what was already there.

Choosing between image formats before you convert

The image format you start with affects the PDF slightly. JPEG files are smaller and work well for photographs. PNG files are larger but preserve detail better and support transparency. TIFF files are used for scans and professional photography but are very large.

For most purposes, it does not matter which format you convert from — the PDF will look the same. If you are converting a scan or a document photo, TIFF or PNG will give you a sharper result. If you are converting a regular photograph, JPEG is fine and produces a smaller PDF.

If you have a choice of formats and the file size matters (for example, you need to email it), convert from JPEG. If sharpness matters more than file size, convert from PNG or TIFF.

Frequently Asked Questions

Can I convert a PDF back to an image?

Yes, but the process is called "exporting" rather than converting. Most PDF readers (including Preview on Mac and the free Adobe Reader) let you right-click a PDF page and export it as an image. Online tools like CloudConvert also do this. The image quality depends on the resolution of the original PDF.

What if my image is a screenshot?

Screenshots convert to PDF the same way as any other image. On Windows, use Print to PDF. On Mac, use Preview. The PDF will be the same size as the screenshot — usually smaller than a full photograph because screenshots are typically 1920 by 1080 pixels or similar.

Does converting to PDF make the file smaller?

Not usually. A PDF is just a container format — the image inside stays the same size. In rare cases, the PDF format itself adds a small amount of overhead, making the file slightly larger. If you need a smaller file, compress the image before converting.

Is it safe to use online image-to-PDF converters?

Most reputable converters (CloudConvert, Zamzar, ILovePDF) delete files after a few hours and use encryption during upload. But if your image contains sensitive information, the built-in method is safer because the file never leaves your computer. Check the privacy policy of any online tool before uploading.

Can I edit the image after I convert it to PDF?

Not easily. Once an image is in a PDF, you cannot edit it the way you would in an image editor. You can add text, annotations, or new pages to the PDF using a PDF editor, but changing the image itself requires converting the PDF back to an image, editing it, and converting again.