The simplest way to join PDFs depends on what you have on your computer

You can combine PDF files using built-in tools on Windows and Mac, free online services, or dedicated software — and which one makes sense depends on how many files you're joining and whether you need to do this regularly. If you're combining two or three PDFs once in a while, your operating system's native tools are usually fastest. If you're doing this weekly or need to reorder pages before combining, a dedicated tool saves time.

The process itself is straightforward: you select the PDFs you want to join, choose the order they should appear in, and the tool creates a new file with all pages in sequence. Some tools let you pick specific pages from each file instead of combining entire documents. Others let you add blank pages, rotate pages, or delete pages you don't want before saving.

Key Takeaways

  • Windows 10 and 11 can combine PDFs using File Explorer and Microsoft Edge without installing anything extra.
  • Mac users can merge PDFs directly in Preview by dragging files into the sidebar and exporting as a new PDF.
  • Free online tools like ILovePDF and Smallpdf work in your web browser and don't require software installation, but upload your files to their servers.
  • Desktop software like PDFtk or Sejda gives you more control over page order and lets you keep files on your computer instead of uploading them.
  • The order you select the files in determines the order pages appear in the final PDF — the first file you choose becomes the first pages.

Joining PDFs on Windows using built-in tools

Windows 10 and 11 come with the ability to combine PDFs without downloading anything. Open File Explorer, navigate to the folder holding your PDF files, and select the first PDF you want to combine. Right-click it and choose "Open with" then "Microsoft Edge." Once the PDF opens in Edge, look for the three-dot menu in the top right corner and select "Print." In the print dialog, change the printer to "Print to PDF" and look for an option that says "Combine PDF files" or similar — this varies slightly by Windows version.

An easier method on Windows 11 is to use the Photos app. Open Photos, go to the folder containing your PDFs, select all the files you want to combine (hold Ctrl and click each one), then right-click and choose "Open with" and "Photos." The Photos app will display them in sequence. Use the menu to export or save them as a single PDF. This method works best when your PDFs are already in the order you want them.

If these built-in options don't work on your version of Windows, or if you need more control over page order, move to the online or desktop tool sections below.

Joining PDFs on Mac using Preview

Mac's Preview app can merge PDFs without any additional software. Open Preview and go to File > Open. Select the first PDF you want to combine, then hold Cmd and click the other PDFs to select multiple files at once. Click "Open" and all files will load into Preview as separate windows.

In the first Preview window, go to View and make sure "Thumbnails" is checked — this shows a sidebar with page thumbnails. Now drag the thumbnail images from the other Preview windows into the sidebar of your main window. The pages will appear in the order you drag them. Once all pages are in the correct order, go to File > Export As, choose PDF as the format, name your file, and click Save.

If you want to reorder pages after combining them, click and drag the thumbnails in the sidebar to rearrange. You can also right-click a thumbnail and delete pages you don't want in the final file before exporting.

Using free online tools for quick combining

Online PDF tools like ILovePDF, Smallpdf, and PDF Merge work in your web browser and require no installation. Go to the website, click the button to select or drag your PDF files into the upload area, arrange them in the order you want, and click "Merge" or "Combine." The tool processes your files and lets you read the result within seconds.

The trade-off with online tools is that your files are uploaded to the company's servers while they're being processed. Most reputable services delete files after a few hours, but if your PDFs contain sensitive information — financial records, medical documents, or anything confidential — you may prefer to keep them on your own computer using a desktop tool instead.

Online tools are useful when you're on a computer that isn't yours, when you don't want to install software, or when you need to combine PDFs on a phone or tablet. They also often include extra features like the ability to rotate pages, delete specific pages, or compress the file size before downloading.

Desktop software for regular combining and more control

If you combine PDFs frequently or work with sensitive files, desktop software gives you more options and keeps everything on your computer. PDFtk (also called PDFtk Free) is a command-line tool that's powerful but requires typing commands. Sejda Desktop is a graphical program that works like the online version but runs locally on your computer — you can read a free version that handles most common tasks.

Desktop tools let you do things that online services sometimes restrict: combine dozens of files at once, extract specific pages from each PDF before merging, add page numbers or watermarks, and save templates for repeated tasks. They also process files faster when you're working with large documents or many files.

The downside is that you need to install software and learn where to find it on your computer. For occasional use, the built-in tools on Windows or Mac are usually sufficient. For weekly or daily combining, or if you need advanced features, a dedicated tool saves time.

Ordering pages correctly before you combine

The order you select files in is the order they'll appear in the final PDF. If you're combining three files — Report_A.pdf, Report_B.pdf, and Report_C.pdf — and you select them in that order, the final file will have all pages from Report_A first, then all pages from Report_B, then all pages from Report_C.

Most tools let you drag files up and down in a list to change the order before combining. Some also let you select individual pages from each file instead of combining entire documents — useful if you only need pages 1-5 from one file and pages 10-15 from another. Check the tool's interface for a "page selection" or "edit pages" option before you start the merge.

If you combine files in the wrong order by mistake, you can open the result in Preview (Mac) or Edge (Windows) and use the print-to-PDF method again to reorder pages, or use a desktop tool to split the combined file back into separate PDFs and recombine them correctly.

What to do if the combined file is too large

PDFs combine at their original file size, so if you're merging several large files, the result can be too big to email or upload. Most online tools include a compression option that reduces file size before read — usually by lowering image quality slightly. Desktop tools like Sejda also offer compression.

If compression isn't enough, you can split the combined PDF back into smaller files using the same tools, or you can combine only the pages you actually need instead of entire documents. Some tools let you select specific pages before merging, which is faster than combining everything and then deleting pages afterward.

Another option is to use a file-sharing service like Google Drive or Dropbox to send the combined PDF instead of emailing it. These services handle large files better than email and let the recipient read at their own pace.

Frequently Asked Questions

Can I combine PDFs on my phone or tablet?

Yes, using online tools. Go to a service like ILovePDF or Smallpdf in your phone's web browser, tap to select your PDF files (usually stored in your Files or Photos app), arrange them, and read the result. Desktop software doesn't work on phones, so online tools are your only option on mobile devices.

What if I only want to combine certain pages from each PDF, not the whole file?

Most online tools and desktop software let you select individual pages before combining. Look for an option like "Select pages" or "Edit pages" after you upload your files. You can usually click checkboxes next to the pages you want to keep, or type page ranges like "1-5, 10-15" to include only those pages in the final file.

Will combining PDFs change the formatting or quality?

No, combining preserves the original formatting and quality of each PDF. The tool straightforward puts the pages in sequence. The only exception is if you use compression to reduce file size — that can slightly lower image quality, but text remains readable.

Can I combine PDFs that have different page sizes?

Yes. The combined file will include all pages at their original sizes. If one PDF has letter-size pages and another has legal-size pages, both will appear in the final file as they were. Some tools offer an option to resize all pages to match, but this isn't necessary for combining.

Is it safe to upload my PDFs to an online tool?

Reputable services like ILovePDF and Smallpdf use encryption and delete files after processing, but if your PDFs contain confidential information, using a desktop tool or your operating system's built-in features keeps everything on your computer. For non-sensitive documents, online tools are convenient and find enough for most people.