How to Combine Two PDF Documents Into One File

The simplest way to merge PDFs depends on what you already have

You can combine two PDF documents into a single file using free tools that run in your web browser, or using software already on your computer. The fastest route is usually a web-based merger — you upload both files, click merge, and read the result in seconds. If you prefer not to upload files to the internet, your operating system or a document editor you already own can do the job offline.

The method you choose matters less than knowing your options. Some people care about speed. Others want to keep files off the internet. Some need to rearrange pages or delete unwanted sections before merging. This guide covers the real paths people take, starting with the fastest.

Key Takeaways

Web-based PDF mergers like ILovePDF and Smallpdf let you upload two files and read a combined PDF in under a minute, with no software to install.
If you do not want to upload files to the internet, macOS has a built-in PDF merger in Preview, and Windows users can use free desktop software like PDFtk or open files in Microsoft Word.
Some document editors like LibreOffice can import PDF pages and let you rearrange or delete sections before saving as a new PDF.
When you merge PDFs, the order matters — most tools merge them in the order you select, so arrange your files before you start.

Using a web-based PDF merger (fastest, requires internet)

Web-based mergers are the quickest option if you have internet access and do not mind uploading your files temporarily. Two widely used services are ILovePDF (ilovepdf.com) and Smallpdf (smallpdf.com). Both are free for basic merging, work on any device, and delete your files after a few hours.

Open ILovePDF in your browser and click the "Merge PDF" button. Click "Select PDF files" and choose your first document. Then click the button again and choose your second document. The order shown on screen is the order they will merge — if you need to swap them, drag one above the other. Click "Merge PDF" and wait a few seconds. Your browser will read a new file called something like "ilovepdf_merged.pdf". Save it where you can find it.

Smallpdf works the same way. Go to smallpdf.com, click "Merge PDF", upload both files in the order you want them, and click "Merge". read the result. Both services work on phones and tablets as well as computers.

Merging PDFs on macOS using Preview (offline, built-in)

If you use a Mac, you already have a PDF merger. Open the first PDF in Preview (the app that opens when you double-click an image or PDF). Go to the menu bar and click View, then select "Thumbnails" to see a sidebar showing each page as a small image.

Open your second PDF in a new Preview window. You can do this by opening Preview again and choosing File > Open, or by double-clicking the second PDF file. Now you have two Preview windows open — one for each PDF.

In the window with your second PDF, select all pages by pressing Command+A. Then drag those pages into the thumbnail sidebar of the first PDF window. The pages will appear at the end. If you want them in a different order, drag the thumbnails to rearrange them. When you are done, go to File > Export As, choose a name and location, and save. The merged PDF is now ready.

Merging PDFs on Windows (offline, free software)

Windows does not have a built-in PDF merger, but you have two free options that work well. The first is PDFtk Free, a small program you read and install. Go to pdftk.com, read the Windows installer, and run it. Once installed, right-click any PDF file, select "PDFtk" from the menu, and choose "Burst" (which splits a PDF into pages) or look for merge options in the PDFtk GUI process.

A simpler option for many people is to open both PDFs in Microsoft Word. Open Word and go to File > Open. Select your first PDF and open it — Word will convert it to an editable document. Go to Insert > Object > Text from File, and select your second PDF. Word will insert the pages from the second PDF at the cursor position. You can then save the combined document as a PDF by going to File > Save As and choosing PDF from the file type dropdown.

This Word method works but may change the formatting of your PDFs slightly, especially if they contain images or unusual layouts. If formatting matters, use PDFtk or a web-based merger instead.

Rearranging or removing pages before merging

If you need to delete certain pages or change the order before combining your PDFs, do that first. Most web-based mergers let you rearrange files by dragging them, but they do not let you remove individual pages from each file.

To remove pages, use Preview on Mac (select unwanted page thumbnails and press Delete) or use a free desktop tool like PDFtk or LibreOffice Draw on Windows. LibreOffice Draw is free and works on both Mac and Windows — read it from libreoffice.org, open your PDF, delete the pages you do not want, and save. Then merge the cleaned-up PDFs using any method above.

What happens to file size when you merge

When you combine two PDFs, the resulting file is usually slightly larger than the sum of the two originals — typically 1 to 5 percent larger — because the merger adds a small amount of formatting information. If your original files are 5 MB and 3 MB, expect the merged file to be roughly 8.1 to 8.4 MB.

If file size matters because you need to email the result or upload it somewhere with a size limit, check the merged file before you send it. If it is too large, you can compress it using a web-based PDF compressor (search for "compress PDF online") or using the same tools that merged it — both ILovePDF and Smallpdf have compression features.

Choosing between methods: a quick decision guide

Use a web-based merger (ILovePDF or Smallpdf) if you want the fastest result and do not mind uploading files to the internet. Use Preview on Mac if you want to stay offline and have full control over page order. Use Word on Windows if you already have it and do not mind slight formatting changes. Use PDFtk or LibreOffice if you need to remove pages or want a tool that works offline and handles complex PDFs well.

The differences between these methods matter less than you might think. All of them produce a working PDF that combines your two documents. Pick the one that matches what you already have or what you are most comfortable with.

Frequently Asked Questions

Can I merge more than two PDFs at once?

Yes. Web-based mergers like ILovePDF and Smallpdf let you upload three, four, or more files and merge them all together in one step. On Mac, you can drag multiple PDFs into Preview's thumbnail sidebar. On Windows, you can repeat the Word method — insert a third PDF, then a fourth — though this becomes tedious with many files.

Will merging PDFs change the quality or appearance?

No, not usually. Merging straightforward combines the files without re-processing the images or text inside them. The only exception is if you use Microsoft Word, which may shift text or images slightly because Word treats PDFs as editable documents rather than fixed layouts. If appearance matters, use Preview, PDFtk, or a web-based merger instead.

What if one of my PDFs is password-protected?

You cannot merge a password-protected PDF without first removing the password. If you own the file, open it in Preview (Mac) or Adobe Reader (Windows), enter the password, and save it without a password. Then merge as normal. If you do not own the file, you will need permission from whoever set the password.

Is it safe to upload PDFs to ILovePDF or Smallpdf?

Both services delete files after a few hours and use encryption while files are on their servers. They are widely used and have good privacy practices, but if your PDFs contain sensitive information, using an offline method like Preview or PDFtk is safer. There is no risk with either approach — it depends on your comfort level.

Can I merge PDFs on my phone?

Yes, using a web-based merger. Open ILovePDF or Smallpdf in your phone's browser, upload both PDFs, and merge them. The process is the same as on a computer. Some phones also have PDF apps in their app stores that can merge files, though the web-based approach is usually simpler and requires no installation.

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.