How to Combine Two PDF Files Into One

The fastest way depends on what you have on your computer

You can merge two PDFs on Windows using built-in tools, on Mac using Preview, or online using free websites that don't require installation. The method that works best depends on whether you want to keep the files on your computer, whether you're comfortable uploading to the internet, and what operating system you use. Most methods take under five minutes once you know the steps.

If you merge PDFs only once or twice, an online tool is usually fastest because there's nothing to install. If you do this regularly, Mac Preview or desktop software saves time in the long run. Windows users without Preview will find online tools simpler than the Print to PDF workaround.

Key Takeaways

Mac users can open both PDFs in Preview, drag pages from one into the other, and save as a new file in seconds.
Windows 11 and later can merge PDFs through Print to PDF, though this requires a workaround and is slower than Mac Preview.
Free online tools like ILovePDF, Smallpdf, and PDF Merge let you upload two files and download the combined result without installing software.
Desktop software like Adobe Acrobat (paid) and free alternatives like LibreOffice can merge files but require installation and make sense only if you merge regularly.
Online tools are fastest for one-time merges, while Preview on Mac is fastest overall if you have a Mac.

Merging PDFs on Mac using Preview

Preview, the built-in Mac image and PDF viewer, can combine PDFs in about two minutes. Open the first PDF in Preview, then look at the sidebar on the left where you see all the pages as thumbnails. Drag the second PDF file directly into that sidebar below the last page of the first PDF. The pages from the second file will insert into the first document in the order you drop them.

Once both PDFs are in the same Preview window, go to File and select Export As. Choose PDF from the format dropdown, give the merged file a new name, and click Save. Your two PDFs are now one file. This method works on any Mac and requires no additional software or internet connection. If you want to rearrange pages before saving, click and drag individual page thumbnails in the sidebar to reorder them.

Merging PDFs on Windows using Print to PDF

Windows 11 and later have a built-in Print to PDF feature, but merging requires extra steps. Open the first PDF in Microsoft Edge or another browser, then go to File > Print. Select "Microsoft Print to PDF" as the printer and save this as a temporary file with a name like "temp1.pdf". Repeat this process with the second PDF, saving it as "temp2.pdf".

After you have both temporary files, use a free online tool like ILovePDF or PDF Merge to combine them into one final file. This workaround is slower than using Mac Preview because Windows lacks a native merge tool built into the file manager. Most Windows users find that skipping the Print to PDF step and going straight to an online tool saves time overall.

Using free online PDF merger tools

Websites like ILovePDF, Smallpdf, and PDF Merge let you upload two PDFs and download the combined file without installing anything. Go to the website, click the button to select or drag your first PDF into the upload area, then add your second PDF. The tool merges them in seconds and gives you a download link. No account is required on most of these sites for a single merge.

The trade-off is that your files travel to the internet. Most reputable PDF tools delete uploaded files within hours, but if your PDFs contain sensitive information, this method may not feel safe. Check the website's privacy policy before uploading. For most everyday PDFs, online tools are the fastest option because they work on any computer, any operating system, and require no setup or installation.

Using desktop software for regular merging

If you merge PDFs often, installing software on your computer makes sense. Adobe Acrobat (paid subscription) has a dedicated Combine Files tool that merges multiple PDFs in one step and lets you reorder pages before saving. Free alternatives include LibreOffice Draw, which can open PDFs and export them as new files, and PDFtk, a command-line tool for people comfortable with technical steps.

Desktop software is slower to set up than online tools but faster once installed if you do this task repeatedly. Adobe Acrobat also lets you delete pages, rotate pages, and adjust page order before saving, which most online tools don't allow. For one-time merges, the setup time usually isn't worth it, but if you merge PDFs weekly or monthly, installation pays for itself in time saved.

Reordering pages before saving the merged file

Some methods let you arrange pages from both PDFs before saving the final file. In Mac Preview, after dragging the second PDF into the sidebar, you can click and drag individual page thumbnails to rearrange them in any order. In Adobe Acrobat, the Combine Files tool shows thumbnails of every page and lets you drag them into any order you want before you save.

Most online tools merge files in the order you upload them and don't let you rearrange pages afterward. If page order matters for your task, use Preview on Mac, Adobe Acrobat on any computer, or merge the files online first and then use Preview or another tool to rearrange them in a second step. This two-step approach takes a few extra minutes but gives you full control over the final order.

What to do if one PDF is scanned or image-based

A scanned PDF is a photograph of a document rather than text that a computer can read. Merging a scanned PDF with a regular PDF works the same way using any of the methods above — the tools don't care whether the PDF contains text or images. The merged file will be larger if one PDF is scanned, because image files take up more space than text-based PDFs.

If you need to edit text inside a scanned PDF before merging, you'll need optical character recognition (OCR) software, which converts the image of text into actual text you can edit. Adobe Acrobat includes OCR, but most free online tools don't. For a simple merge of a scanned PDF and a regular PDF without editing, any of the methods described above will work without any extra steps.

Frequently Asked Questions

Can I merge more than two PDFs at once?

Yes. Most online tools and desktop software can merge three, four, or more PDFs in one step. Mac Preview can drag multiple PDFs into the sidebar one after another. Adobe Acrobat's Combine Files tool accepts unlimited PDFs. Online tools usually have a button to add more files after you've selected the first two.

Will the merged PDF be larger than the original two files combined?

Usually slightly larger because the merge process adds formatting and structure information. The difference is typically small — a few percent. If file size matters, check the size of the merged PDF after saving and compare it to the original two files added together.

Can I undo a merge after I've saved the file?

No. Once you save the merged PDF, the original two files are not recoverable from it. Keep your original PDFs in a separate folder before merging, so you can go back to them if needed.

Do online PDF tools keep copies of my files?

Reputable tools like ILovePDF and Smallpdf delete uploaded files within a few hours. Check the privacy policy on the website before uploading if your PDFs contain sensitive information. For highly confidential documents, use Mac Preview or desktop software instead.

What if the merged PDF looks different from the originals?

Formatting sometimes shifts slightly during a merge, especially if the PDFs have different page sizes or fonts. Preview the merged file before deleting the originals. If the formatting is wrong, try a different tool — some handle formatting better than others.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.