The fastest way to combine PDFs depends on what you have

The simplest method is to use your operating system's built-in tools or a free online merger — you do not need special software. On Windows, you can use Microsoft Edge or a free tool like ILovePDF. On Mac, Preview handles it in three steps. If you work with PDFs constantly, a dedicated tool like Adobe Acrobat or PDFtk gives you more control, but for a one-time merge, the free options work just as well.

The process itself is straightforward: you upload or open both files, arrange them in the order you want, and save the result. Most tools let you choose whether the second PDF goes at the end or inserts at a specific page. This guide covers the three most common routes — the one you pick depends on whether you want to stay online, use software you already own, or download something new.

Key Takeaways

  • Microsoft Edge on Windows and Preview on Mac both merge PDFs without downloading anything extra.
  • Free online tools like ILovePDF and Smallpdf work on any computer but require you to upload files to their servers.
  • The merged file is a new document — your original PDFs stay unchanged.
  • You control the page order before merging, so you can put either PDF first.

Merging PDFs in Microsoft Edge on Windows

Microsoft Edge has a built-in PDF editor that lets you combine files without leaving the browser. Open Edge, go to your first PDF file, and right-click on it in File Explorer, then select "Open with" and choose Microsoft Edge. Once the file opens in Edge, look for the pencil icon in the toolbar at the top right — this opens the editing tools.

Click the three-dot menu (next to the pencil icon) and select "Organize pages." This view shows your first PDF as a series of thumbnails. At the bottom of the window, you will see an "Insert" button. Click it, navigate to your second PDF file, and select it. Edge will add all pages from the second PDF to the end of the first one. If you want the second PDF to go somewhere other than the end, drag its thumbnail pages to the position you want. When you are done, click "Save a copy" in the top menu to download your merged file.

Merging PDFs in Preview on Mac

Preview, the default PDF viewer on Mac, has a thumbnail sidebar that makes combining files straightforward. Open your first PDF in Preview. Then open your second PDF in a new Preview window — do this by going to File > Open and selecting the second file while the first is still open. You now have two Preview windows side by side.

In the window with your second PDF, select all pages by pressing Command+A, then copy them with Command+C. Switch to the window with your first PDF, click at the end of the document (or wherever you want to insert the pages), and paste with Command+V. The pages from the second PDF will insert at that location. Go to File > Export as PDF and choose where to save your merged document. Your original files remain unchanged.

Using a free online PDF merger

If you prefer not to use your operating system's tools, free online services like ILovePDF, Smallpdf, and PDF Merge work on any computer. Go to the website, click "Select PDF files" or a similar button, and upload both PDFs. The tool will show you thumbnails of all pages from both files. Drag and drop the pages to arrange them in the order you want — you can even mix pages from each file if needed.

Once you have the order right, click "Merge" or "Combine," and the tool will process your files. Download the result to your computer. The main trade-off with online tools is that your files are uploaded to someone else's server temporarily. Most reputable services delete files after a few hours, but if you work with sensitive documents, the offline methods (Edge or Preview) are safer.

What happens to your original files

No matter which method you use, your original PDFs are never changed. The merge creates a new file that contains pages from both documents. When you save or download the merged result, you are saving a separate file. Your two original PDFs stay exactly as they were. This means you can merge the same two files multiple times with different page orders if you need to.

When you save the merged file, give it a clear name that reflects its contents — something like "Contract_and_Signature_Page.pdf" rather than "Merged.pdf" makes it easier to find later. Most tools save to your Downloads folder by default, so check there if you cannot find the file right away.

Arranging pages before you merge

All three methods let you see pages from both PDFs before you finalize the merge. In Edge and Preview, you work with thumbnails — small previews of each page — and drag them into the order you want. Online tools show the same thumbnails and let you reorder by dragging. This means you can put pages from the second PDF in the middle of the first one if that is what you need, not just at the end.

Take a moment to check the page order before you click the final merge button. It is much easier to rearrange now than to split the files apart later. If you realize you want pages in a different order after merging, you can always merge again with a different arrangement.

When you need more control over the merge

The methods above work for straightforward merges, but if you need to remove specific pages, rotate pages, or add blank pages between documents, you may want a more advanced tool. Adobe Acrobat (paid) and free alternatives like PDFtk or LibreOffice Draw give you page-level control. These tools let you delete unwanted pages, rotate individual pages, and insert blank pages or content from other files at exact locations.

For most people combining two complete documents, the built-in tools are enough. But if you find yourself regularly needing to edit PDFs — removing pages, changing page order, or adding annotations — a dedicated PDF editor might save you time. Many of these tools are free, though some have paid versions with extra features.

Frequently Asked Questions

Can I merge more than two PDFs at once?

Yes. Online tools and dedicated PDF software let you upload three, four, or more files and arrange all of them together. With Edge or Preview, you can merge two files, then merge that result with a third file, though it takes more steps. Most people find online tools faster for combining many files at once.

Will the merged file be larger than the originals?

The merged file will be roughly the size of both originals added together, sometimes slightly smaller due to compression. If your two PDFs are 5 MB and 3 MB, expect the merged file to be around 7 to 8 MB. The exact size depends on the compression method the tool uses.

What if one PDF is in a different format or looks strange?

PDFs created from scans, images, or older software sometimes look odd when merged with newer PDFs. The merge itself will still work — the pages will combine correctly. If the appearance bothers you, open the merged file in your PDF viewer to confirm it looks acceptable before sharing it with others.

Can I undo a merge if I made a mistake?

The merge creates a new file, so your originals are safe. If you merged in the wrong order or included the wrong pages, simply delete the merged file and start over. You have not lost anything. If you saved over one of your original files by accident, you may not be able to recover it, so always check the filename before saving.

Is it safe to use online PDF tools with confidential documents?

Reputable services encrypt files during upload and delete them after processing, usually within a few hours. However, if your documents contain highly sensitive information, using Edge or Preview keeps everything on your own computer. Choose based on your comfort level with uploading files to external servers.