The fastest way depends on what you already have open

If you have a document editor open already — whether that's a privacy-focused one or a mainstream tool — you can usually combine PDFs without leaving it. Most editors let you insert pages from other PDFs directly into your current document, then save the result as a single file. The steps change slightly depending on which program you use, but the idea is the same: open your first PDF, then add pages from the others in order.

If you do not have an editor open yet, your choice of tool matters more. Some programs handle PDF merging as a built-in feature. Others require you to convert PDFs to a different format first, combine them, then convert back to PDF — which takes longer and sometimes reduces image quality. A few programs do the work in your browser without storing your files on anyone's server, which matters if you care about what happens to your documents.

Key Takeaways

  • Most document editors can insert pages from one PDF into another, then save the combined result as a new PDF file.
  • Browser-based PDF tools like Smallpdf and ILovePDF let you upload multiple PDFs and merge them without installing software, though your files pass through their servers.
  • Desktop programs like LibreOffice and Microsoft Word can combine PDFs, but the process varies — some require you to convert to another format first.
  • If privacy is your main concern, a local tool like PDFtk or a command-line program keeps your files on your own computer instead of uploading them.
  • The quality of the final PDF depends on whether you merge at the file level (best) or convert to another format and back (may lose detail).

Using the document editor you already have

If you are working in Microsoft Word, open the first document you want to combine. Go to the Insert tab, select Object, then choose Text from File. Navigate to the second PDF and select it. Word will import the pages into your document. Repeat for each additional PDF. When you are done, save the file as a PDF using File > Save As and choose PDF from the format menu.

In LibreOffice Writer, the process is similar but uses different menu names. Open your first PDF, then go to Insert > Text from File. Select the next PDF and click Insert. The pages will appear in your document. Continue for each PDF you want to add, then save as PDF through File > Export as PDF. LibreOffice is free and works on Windows, Mac, and Linux, which makes it useful if you want to avoid paying for software.

Google Docs does not handle PDFs the same way — it converts them to images, which means you lose the ability to search text or copy from the final document. If you are already in Google Docs for another reason, it is better to use a different tool for merging PDFs.

Browser-based tools that work without installation

Smallpdf, ILovePDF, and PDF Merge are web-based tools that let you upload multiple PDFs, arrange them in the order you want, and read the combined file. You do not need to install anything — you just visit the website, upload your files, and the tool does the work. These are fast and straightforward, especially if you only merge PDFs occasionally.

The trade-off is that your PDFs are uploaded to the company's servers while the merge happens. Smallpdf and ILovePDF both say they delete files after a few hours, but your documents do pass through their systems. If the PDFs contain sensitive information — medical records, financial statements, legal documents — you may prefer a tool that keeps everything on your own computer. Check the privacy policy of whichever tool you choose to see how long they keep files and whether they use them for any other purpose.

Most of these tools are free for a limited number of merges per month, then charge a subscription fee if you need more. If you merge PDFs regularly, the cost adds up, and a desktop program might be cheaper in the long run.

Desktop programs that stay on your computer

PDFtk (PDF Toolkit) is a command-line program that combines PDFs without uploading them anywhere. If you are comfortable opening a terminal or command prompt, you can merge files with a single line of text. For example, the command pdftk file1.pdf file2.pdf cat output merged.pdf combines two PDFs into one. PDFtk is free and works on Windows, Mac, and Linux. The downside is that it requires some technical comfort — you need to know how to navigate folders and type commands.

If you want a graphical interface instead of a command line, PDF Shuffler (Linux only) and PDFMerge (Windows) both let you drag and drop PDFs, arrange pages, and save the result. These are simpler than PDFtk but less powerful — they do the basic job without extra features. Both are free and open-source, which means the code is public and anyone can review it for security issues.

For Mac users, Preview (the built-in image and PDF viewer) can combine PDFs. Open the first PDF in Preview, then drag the second PDF into the sidebar on the left. The pages will appear in order. You can rearrange them by dragging, then save the result as a new PDF. This is the simplest option if you use a Mac and do not want to install anything.

When to convert instead of merge

Some PDFs are actually images — scanned documents, photographs, or pages created from images rather than text. If you try to merge image-based PDFs with text-based PDFs, the result may look odd or the text may not be searchable. In these cases, converting all PDFs to images first, combining them, then converting back to PDF can produce a more consistent result.

This process takes longer and may reduce quality, especially for text-heavy documents. Use this approach only if your PDFs are a mix of formats and the final document does not need to be searchable. For most everyday merging, combining at the file level (the method described above) is faster and better.

Organizing pages before you merge

Before you combine PDFs, decide what order the pages should be in. Most tools let you rearrange pages after upload, but it is easier to get it right beforehand. If you are combining documents from different sources — a cover page, several reports, an appendix — number them or rename the files so you know which comes first.

Some tools also let you delete pages you do not need before merging. If a PDF has a blank page or a cover sheet you do not want in the final document, remove it first rather than deleting it from the merged file later. This saves a step and keeps the final document clean.

Saving and sharing your merged PDF

Once you have combined the PDFs, save the result with a clear name that describes what it contains — for example, "2024_Tax_Documents_Combined" instead of "Merged_PDF_1". This makes it easier to find later and tells anyone you share it with what they are looking at.

If you are sharing the merged PDF with others, consider whether it contains information you want to keep private. Some PDFs include metadata — hidden information about who created the file, when, and sometimes comments or tracked changes. Before sharing, open the file in your document editor and check File > Properties (or File > Document Properties in LibreOffice) to see what metadata is attached. You can usually remove it from the same menu.

Frequently Asked Questions

Can I merge PDFs that have different page sizes?

Yes, most tools will combine them, but the result may look uneven if one PDF has letter-size pages and another has legal-size pages. The pages will appear at their original sizes in the merged document. If you want them to look uniform, you may need to resize the PDFs before merging, which most document editors can do through the print-to-PDF feature.

Will merging PDFs make the file size larger?

The merged file will be roughly the size of all the original PDFs added together. If you are combining three 5-megabyte PDFs, expect a file around 15 megabytes. Some tools compress the result slightly, but not by much. If file size matters — for example, you need to email it — check the final size before sending.

What if one of my PDFs is password-protected?

Most merging tools cannot read password-protected PDFs. You will need to remove the password first. Open the PDF in your document editor, go to File > Properties, and look for security or password settings. You can usually remove the password from there, then merge as normal.

Can I undo a merge if I make a mistake?

Once you save the merged PDF, you cannot easily separate it back into the original files. Always keep the original PDFs in case you need to start over. If you realize you made a mistake after saving, you can open the merged file and delete the pages you do not want, then save it again.

Is there a limit to how many PDFs I can combine?

Desktop programs and browser tools usually have no hard limit, but very large merges (50+ PDFs) may slow down your computer or cause the tool to time out. If you are combining many files, do it in batches — merge the first 10, then merge that result with the next 10, and so on.