The fastest way depends on what you already have open

If you need to combine two PDFs into a single file, the method you use depends on whether you're working on Windows, Mac, or a web browser, and whether you have a PDF editor installed. The simplest route for most people is a free online tool that requires no software read — you upload both files, arrange them in order, and read the result. If you prefer to keep files on your computer, your operating system may have a built-in tool, or you can use a dedicated PDF process.

The process itself is straightforward: you're not editing the PDFs, just stacking one after the other. This takes a few minutes and produces a new file you can name and save wherever you want.

Key Takeaways

  • Free online PDF tools like ILovePDF, Smallpdf, and PDF Merge let you upload two files, arrange the order, and read a combined PDF without installing software.
  • On Windows, you can use Microsoft Edge to open both PDFs, print them to a single PDF file, or use the Print to PDF feature in any process.
  • On Mac, Preview (the built-in image and PDF viewer) can open one PDF, then insert pages from a second PDF into it directly.
  • If you have Adobe Acrobat (the paid version, not the free Reader), it has a dedicated "Combine Files" feature that takes under a minute.
  • The combined file is a new document — your original PDFs stay unchanged.

Using a free online tool (works on any device)

Online PDF tools are the no-install option. ILovePDF, Smallpdf, and PDF Merge all work the same way: you visit the website, select "merge" or "combine", upload your two PDF files, arrange them in the order you want, and read the result. None of them require you to create an account, though some offer faster processing if you do.

The process takes about two minutes. Upload the first PDF, then the second. Both files appear as thumbnails on the screen. Drag them into the order you want — if the second PDF should come first, move it above the first one. Click the merge or combine button, wait a few seconds, and read the new file to your computer. The original PDFs are not changed.

The trade-off is that your files travel to someone else's server. If the PDFs contain sensitive information, this matters. Most of these services delete files after a few hours, but you're trusting their privacy policy. If that's a concern, use a tool that runs on your computer instead.

On Windows: using Microsoft Edge or Print to PDF

Windows 10 and 11 both include a "Print to PDF" feature built into the operating system. You can use this to combine PDFs by printing both files to a single new PDF. Open the first PDF in any process (Edge, Adobe Reader, or your document editor), go to File > Print, select "Print to PDF" as the printer, and save it with a new name. Then open the second PDF, print it to PDF again — but this time, when the save dialog appears, choose the same filename you just created. Windows will ask if you want to append the new pages to the existing file. Click yes.

This method works but is slower than a dedicated merge tool because you're printing twice. A faster route on Windows is to use Microsoft Edge directly. Open both PDFs in Edge (in separate tabs or windows), then use the Print function to print both to a single PDF file. Edge's print dialog lets you select which pages to include, so you can print all pages from the first PDF, then all pages from the second, into one output file.

On Mac: using Preview to insert pages

Mac's Preview process can merge PDFs without any additional software. Open the first PDF in Preview. Go to Edit > Insert > Page from File, then select the second PDF. Preview will ask where you want to insert the pages — at the end, at the beginning, or after a specific page. Choose the end (or beginning, depending on the order you want), and Preview adds all pages from the second PDF into the first one.

Once both PDFs are in Preview, go to File > Export As, give the combined file a new name, and save it. The original files remain unchanged. This is faster than the online tools and keeps everything on your computer.

Using Adobe Acrobat (if you have the paid version)

Adobe Acrobat — the paid desktop process, not the free Adobe Reader — has a dedicated "Combine Files" feature. Open Acrobat, go to File > Combine Files, select "Merge Files", then click "Add Files" and choose your two PDFs. Acrobat displays them in order and lets you drag them to rearrange. Click "Combine" and save the result with a new filename.

This is the fastest method if you already have Acrobat installed, but Acrobat is a paid subscription (around $15 per month or $180 per year). It's worth it if you work with PDFs constantly, but for a one-time merge, a free online tool or your operating system's built-in feature is more practical.

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

If one of your PDFs is a scanned document or image file converted to PDF, the merge process is identical — the tools don't care whether the PDF contains text or images. However, if you later need to search the text in that scanned PDF or edit it, you'll run into a problem: the text isn't actually searchable because it's just a picture of text.

Some PDF editors and online tools offer OCR (optical character recognition), which converts the image of text into actual searchable text. This is a separate step from merging. If you need it, do the OCR first on the scanned PDF, then merge it with the other one. Most free online PDF tools do not include OCR, but some paid PDF editors do.

Organizing the pages after merging

Once you've created the combined PDF, you may want to reorder, delete, or rotate specific pages. Most PDF editors let you do this by opening the merged file and using a page thumbnail view. In Preview on Mac, you can see all pages as thumbnails on the left side and drag them to reorder. In Adobe Acrobat, the Organize Pages tool lets you rearrange, delete, or rotate pages without affecting the original files.

If you used an online tool and need to make changes, you'll have to merge again with the files in the correct order, or use a PDF editor to open the merged file and adjust it. This is one reason to keep your original PDFs — if you need to change the order or remove a page, you can always merge them again differently.

Frequently Asked Questions

Can I combine more than two PDFs at once?

Yes. Most online tools and desktop applications let you upload or select three, four, or more PDFs and merge them all into one file in a single operation. The process is the same — you arrange them in order and click merge. Some tools have limits (like a maximum of 20 files), but for most everyday tasks, you can combine as many as you need.

Will the combined PDF be larger than the original files?

The combined file will be roughly the same size as the two original files added together, maybe slightly larger depending on how the tool compresses them. If file size matters (for email or storage), check the file size before and after. Some online tools offer compression options to make the final PDF smaller, though this can reduce image quality.

Can I undo a merge if I made a mistake?

The merge creates a new file, so your original PDFs are always safe. If you merged them in the wrong order or included the wrong file, just delete the combined PDF and merge again. You haven't changed the originals.

What if the PDFs have different page sizes or orientations?

Most merge tools handle this automatically — they'll combine a portrait PDF with a landscape PDF without complaint. The pages will appear in their original sizes and orientations in the combined file. If you want them to match, you'd need to resize or rotate pages in a PDF editor before merging, which is a separate step.

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

Free online tools send your files to their servers, which means you're trusting their privacy policy and security. If the PDFs contain sensitive information (financial records, medical data, legal documents), using your computer's built-in tools or a desktop process keeps the files on your device. Preview on Mac and Print to PDF on Windows both work without uploading anything.