How to Convert Images to PDF: A Complete Guide

A PDF puts several images into one file that opens and prints the same way on any device. This article compares three ways to make one (a browser-based converter such as Image2PDF, the tools built into Windows and macOS, and desktop software) and the settings that change the result.

Why Convert Images to PDF?

Images stored as individual JPG or PNG files are convenient for editing and sharing on social media, but they fall short when you need to present, archive, or print documents professionally. Converting images to PDF solves several problems at once.

Universal compatibility. PDF is the most widely supported document format in existence. It can be opened on Windows, macOS, Linux, iOS, Android, and virtually every web browser without installing special software. When you send someone a PDF, you can be confident they will be able to view it exactly as you intended, regardless of what device or operating system they use.

Professional presentation. A single PDF file with properly sized pages looks far more polished than a folder of loose image files. If you are sending a proposal, a design mockup, or a set of scanned documents to a client or colleague, packaging them into a PDF conveys attention to detail and makes the content easier to navigate.

Combining multiple images. One of the biggest advantages of PDF conversion is the ability to merge many images into a single file. Instead of attaching ten separate photos to an email, you can combine them into one PDF. This reduces clutter, keeps your images in the correct order, and avoids the risk of a recipient missing an attachment.

Preserving quality for printing. PDFs are designed for print. A PDF can hold an image at its full resolution, so it can print at the same quality as the original. Printing directly from an image viewer leaves the scaling to the print dialog, while a well-constructed PDF fixes the page size and layout in advance.

Easier sharing. Many email services and file-sharing platforms handle PDFs more gracefully than raw images. PDFs keep their page layout in previews, and recipients can scroll through all pages in a single viewer window.

Methods for Converting Images to PDF

There are several ways to convert images to PDF, ranging from free browser-based tools to full desktop applications. The right choice depends on how many images you need to convert, how much control you want over the layout, and whether privacy is a concern.

Method 1: Using a Browser-Based Tool (Recommended)

Browser-based converters are a convenient option for most people. They require no software installation, work on any device with a web browser, and are available immediately. Image2PDF is a free browser-based converter that processes your files on your device, so your images are never uploaded to a remote server.

Here is how to use it:

1. Open the converter. Go to the Image2PDF converter in any modern browser on your computer, phone, or tablet.
2. Add your images. Click or tap the drop area, or drag your image files onto it. You can add up to 20 images (35 MB per image, 200 MB in total) in JPG, JFIF, PNG, WEBP, or BMP format. HEIC photos from an iPhone are not supported; convert them to JPG or PNG first.
3. Arrange your pages. A thumbnail appears for each image. Drag the thumbnails, or use the arrow buttons, to set the page order. Click any thumbnail to see a larger preview.
4. Choose your settings. Page size: Match image (the default, which makes each page the image's pixel size at 96 pixels per inch), US Letter, or A4. Orientation: Auto (the default), Portrait, or Landscape. Scale: Fill (the default, which covers the page and crops whatever overflows) or Fit (which shows the whole image with white margins). Output: Single PDF (the default) or One PDF per image.
5. Download. Click Download PDF. The PDF is built in your browser and saved to your device. If an image cannot be read, it is skipped and you are told which file it was. No account is needed, and your images are not uploaded.

The main advantages of this approach are privacy and simplicity. Because the conversion runs in your browser, it keeps working if your internet connection drops after the page has loaded, although reloading the page while offline will fail. Your images are not sent over the internet. The page itself does load ads, analytics, and the pdf-lib library from third parties, but none of them receive your files.

Method 2: Using Your Operating System's Built-In Tools

Both Windows and macOS include built-in features that can convert images to PDF, though they offer less flexibility than a dedicated tool.

Windows: Microsoft Print to PDF. Select one or more images in File Explorer, right-click, and choose "Print" (on Windows 11 you may need to click "Show more options" first). In the Print Pictures dialog, choose "Microsoft Print to PDF" as the printer, pick a paper size and a layout such as "Full page photo," then click "Print" and choose where to save the PDF. For a single image, you can also open it in the Photos app, print it, and pick "Microsoft Print to PDF" as the printer. The layouts are fixed, and the "Fit picture to frame" option can crop the edges of an image, so check the preview before printing.

macOS: Preview and Quick Actions. Select the images in Finder, right-click, and choose "Open With > Preview" so they open together in one window. Show the sidebar with View > Thumbnails and drag the thumbnails into the order you want. Then select all the thumbnails (click in the sidebar and press Command-A), choose File > Print, and pick "Save as PDF" from the PDF menu at the bottom of the print dialog; each selected image becomes a page. File > Export as PDF only exports a single image, so use Print when you want one PDF with several pages. On macOS Mojave or later there is a quicker route: select the images in Finder, right-click, and choose Quick Actions > Create PDF. Name the files in sequence first if page order matters.

The main limitation of built-in tools is that they work through the print system rather than being built for PDF creation. Page size, margins, and whether an image fits or fills the page depend on the print dialog's options, which differ between Windows and macOS, so check the preview before saving.

Method 3: Using Desktop Software

Desktop applications like Adobe Acrobat and LibreOffice offer the widest range of PDF creation features, but they come with trade-offs.

Adobe Acrobat Pro is the industry standard for PDF editing and creation. It allows you to combine images into a PDF with fine-grained control over page order, size, and layout. However, Acrobat Pro requires a paid subscription, and the software is large and resource-intensive. For a task as simple as converting images to PDF, it is often more tool than you need.

LibreOffice is a free, open-source office suite that can also handle this task. You can insert images into a LibreOffice Writer or Impress document, adjust their size and position, and then export the document as a PDF. This approach gives you full control over layout but requires more manual work than a dedicated converter.

Desktop software makes sense if you already have it installed and need advanced features like adding text annotations, watermarks, or form fields to your PDF. For straightforward image-to-PDF conversion, a browser-based tool is usually faster and simpler.

Tips for Best Results

No matter which method you choose, following these tips will help you produce better PDFs.

Start with high-resolution images. The quality of your PDF is only as good as the images you put into it. If you are scanning physical documents, use a resolution of at least 300 DPI. For photographs, use the largest version of the image available. Avoid images that have been heavily compressed or resized, as compression artifacts will be visible in the PDF, especially when printed.

Choose the right page size. A page size that matches the image, such as Image2PDF's "Match image" setting with Auto orientation, produces pages with the same shape as each image and no white borders. In Image2PDF each page gets the image's pixel size at 96 pixels per inch, so a 4032×3024 phone photo becomes a 42 by 31.5 inch page: fine on screen, but too large to print without scaling. If you plan to print the PDF on standard paper, choose US Letter (8.5 by 11 inches) or A4 (210 by 297 millimeters) depending on your region. Mismatched page sizes can lead to unexpected cropping or large white margins when printing.

Understand Fill vs. Fit scaling. When placing an image on a standard page size, you have two choices. "Fit" scales the image so that the entire image is visible on the page, which may leave white space on two sides. "Fill" scales the image so that it covers the entire page, which may crop the edges of the image. Use Fit when you need to see the complete image, and Fill when you want a clean, borderless page. Fill is Image2PDF's default, and on US Letter or A4 it can crop a lot: a tall 1170×2532 phone screenshot placed on A4 loses about 35% of its height. For documents and screenshots on standard paper sizes, switch to Fit.

Consider file size. PDFs containing many high-resolution images can become quite large. If you need to email the file or upload it to a website with a file size limit, consider using JPG images rather than PNG, since JPG files are typically much smaller. You can also reduce image resolution before conversion if the full resolution is not necessary for your use case.

Reorder images before converting. Take a moment to arrange your images in the correct sequence before generating the PDF. It is much easier to drag thumbnails into the right order in a converter tool than to rearrange pages in a finished PDF. If you are scanning a multi-page document, name your files with numbers (page-01.jpg, page-02.jpg) so they sort correctly when you select them.

Common Image Formats Explained

The format of your source images affects both the quality and the file size of the resulting PDF. Here is a quick overview of the most common formats you will encounter.

JPG (JPEG). The most popular image format for photographs. JPG uses lossy compression, which means it discards some image data to achieve smaller file sizes. This makes JPG images smaller and faster to work with, but each time you edit and re-save a JPG, it loses a small amount of quality. JPG images typically produce the smallest PDFs and are the best choice for photographic content where minor compression artifacts are acceptable. Image2PDF embeds JPG files without re-compressing them; the one exception is a phone photo that has to be rotated upright, which is re-encoded as JPEG at quality 0.92.

PNG. A lossless format that preserves every pixel exactly as it was captured. PNG files are larger than JPGs but are ideal for screenshots, diagrams, text-heavy images, and any graphic with sharp edges or flat colors. PNG also supports transparency, which can be useful for logos and overlays. Image2PDF embeds PNG images losslessly and keeps their transparency, so PDFs made from PNG photos will be larger than PDFs made from JPGs.

WEBP. A modern format developed by Google that supports both lossy and lossless compression. WEBP files are generally smaller than both JPG and PNG at equivalent quality levels, making them an excellent choice for web images. A PDF cannot store WEBP data, though, so Image2PDF decodes WEBP images and re-encodes them as JPEG at quality 0.92, turning any transparent areas white. The page in the PDF can end up larger than the original WEBP file.

BMP. An uncompressed bitmap format that stores raw pixel data without any compression. BMP files are much larger than JPGs of the same image (a 1920×1080 BMP is about 6 MB). Image2PDF re-encodes BMP images as JPEG at quality 0.92, so the PDF is much smaller than the BMP files but no longer lossless. If you need pixel-exact pages, convert BMP files to PNG first.

With Image2PDF, JPG files give the smallest PDFs because they are embedded unchanged. WEBP and BMP images end up as JPEG pages at quality 0.92, and PNG images stay lossless, which makes them large for photographs. For everyday use, JPG images offer the best balance of quality and file size. For documents with text or sharp graphics, PNG is the better choice despite the larger files.