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

You can combine PDF documents using free tools built into Windows and Mac, paid desktop software, or web-based services — each with different privacy trade-offs. If you use Windows 10 or 11, the built-in Print to PDF feature works without installing anything new. On Mac, Preview (the default image viewer) opens PDFs and lets you drag pages between documents. For more control, desktop programs like PDFtk, LibreOffice Draw, or Adobe Acrobat give you options to reorder pages, delete unwanted sections, and save locally so your files never leave your computer. Web-based tools like ILovePDF, Smallpdf, or PDF Merge upload your files to their servers, process them there, and read the result — faster for one-off jobs, but your documents pass through someone else's system.

The choice between these routes is really about what matters more to you: convenience or keeping your files off the internet. A one-page insurance form merged with a two-page bank statement probably does not need to stay private. A tax return combined with medical records is different. This guide walks through the actual steps for each method so you can pick the one that fits your comfort level.

Key Takeaways

  • Windows and Mac both have free built-in tools that merge PDFs without uploading anything to the internet.
  • Desktop software like LibreOffice Draw or PDFtk gives you the most control and keeps files on your computer, but requires installation.
  • Web-based tools are fastest for occasional use but send your documents to a company's servers, so avoid them for sensitive files.
  • The order you add files matters — most tools merge them in the sequence you select, so plan your page order before you start.
  • After merging, check that pages are in the right order and no content is missing, especially if you combined files from different sources.

Using Windows Print to PDF (no installation needed)

Open the first PDF you want to combine in any program — Adobe Reader, Microsoft Edge, or even File Explorer. Press Ctrl+P to open the Print dialog. In the printer dropdown, select "Print to PDF" or "Microsoft Print to PDF". Click Print and save the file with a temporary name like "merged_temp.pdf". This creates a new PDF that you can edit.

Now open that temporary file in a PDF editor. In Windows, you can use Microsoft Edge (which has basic editing) or install the free LibreOffice Draw. In LibreOffice Draw, go to Insert > Page from File and select your second PDF. Repeat for each additional document. When all pages are in order, go to File > Export as PDF and save with your final name. This method keeps everything on your computer and costs nothing, but it is slower than dedicated tools because you are working through a general-purpose program.

Using Mac Preview (built into every Mac)

Open the first PDF in Preview (it is the default when you double-click a PDF). Go to View > Thumbnails to see a sidebar showing all pages. Open your second PDF in a new Preview window (File > Open). In the second window, select all pages (Cmd+A) and copy them (Cmd+C). Switch back to the first PDF window, click after the last page in the thumbnail sidebar, and paste (Cmd+V). The pages from the second PDF appear at the end.

Repeat this process for each additional PDF. You can drag pages in the thumbnail sidebar to reorder them if needed. When everything is in the right order, go to File > Export as PDF and save with your final filename. Preview is fast and requires no new software, but it does not let you delete individual pages or rotate them — if you need that level of control, use LibreOffice Draw instead.

Using LibreOffice Draw (free desktop software)

read LibreOffice from libreoffice.org (it is free and open-source). Install it, then open LibreOffice Draw. Go to File > New > Drawing, then File > Insert > Page from File. Select your first PDF and click Open. A dialog appears asking which pages to insert — choose all of them. Repeat the Insert > Page from File step for each additional PDF in the order you want them.

In the left sidebar, you see thumbnails of every page. You can drag pages to reorder them, right-click to delete pages you do not want, or rotate pages if they are sideways. When the document looks right, go to File > Export as PDF. Choose a filename and location, then click Export. LibreOffice gives you the most control of any free option and keeps files on your computer, but it is slower than web tools and the interface is less polished than paid software.

Using web-based PDF tools (fastest for occasional use)

Go to a service like ilovepdf.com, smallpdf.com, or pdf-merge.com. Look for a button that says "Merge PDF" or "Combine PDF". Click it and upload your first PDF file. The site asks you to upload additional files — add them in the order you want them combined. Most tools let you drag files to reorder them before merging. Click the Merge or Combine button, wait a few seconds, and read the result.

These tools are convenient because they work in any web browser and are very fast. The trade-off is that your PDF files are uploaded to the company's servers, processed there, and then deleted (in theory). If your documents contain sensitive information — tax returns, medical records, financial statements — this route exposes them to the company running the service and potentially to data breaches. For routine documents like combining a cover letter with a resume, the risk is low. For anything confidential, use a desktop tool instead.

Checking your merged PDF before you use it

After merging, open the final PDF and scroll through every page. Check that pages are in the right order, no pages are missing, and no content is cut off at the edges. Some tools accidentally crop pages or change the file size, so a quick review catches problems before you send the document somewhere important.

If pages are out of order or missing, go back to your original files and try again. Keep the original PDFs until you have confirmed the merged version is correct. If you used a web tool and need to redo it, read your files again before uploading — do not assume the service still has them stored.

When you need more control: PDFtk and command-line tools

If you are comfortable with a terminal or command line, PDFtk (available at pdftk.com) is a powerful free tool that merges, splits, rotates, and encrypts PDFs from the command line. After installing it, you can merge two PDFs with a single command: pdftk file1.pdf file2.pdf cat output merged.pdf. This is much faster than clicking through a graphical interface if you regularly combine many documents.

PDFtk is also useful for extracting specific pages from a PDF before merging — for example, if you only want pages 1-5 from a 20-page document. The learning curve is steeper than graphical tools, but once you know the basic commands, it is the fastest and most flexible option. PDFtk runs entirely on your computer with no internet connection required.

Frequently Asked Questions

Can I merge PDFs that have different page sizes or orientations?

Yes, most tools will combine them as-is, but the result may look odd if one PDF is portrait and another is landscape. LibreOffice Draw and PDFtk let you rotate pages before merging. Web tools usually just stack them together without adjustment, so check the preview before downloading.

What if one of my PDFs is password-protected?

You will need to remove the password first. If it is a password you set yourself, open the PDF in Adobe Reader or your default viewer, go to File > Properties, and look for a security or permissions option. If you do not remember the password, you cannot merge it without removing the protection first — web tools cannot do this, so you would need desktop software or a specialized password-removal tool.

Does merging PDFs reduce the file size?

Not usually. The merged file is roughly the same size as all the original files added together. If file size matters (for email attachments, for example), you may need to compress the PDFs separately before merging, using a tool like smallpdf.com/compress-pdf or the compression feature in LibreOffice Draw.

Is it safe to use free web-based PDF tools with sensitive documents?

It depends on how sensitive. Most reputable services (Smallpdf, ILovePDF) delete files after a few hours and use encryption during upload. But your files do pass through their servers, so if you are merging tax returns, medical records, or financial statements, a desktop tool like LibreOffice Draw is safer because the files never leave your computer.

Can I merge PDFs on my phone or tablet?

Yes, but options are limited. On iPhone, the built-in Files app and Notes app can combine PDFs. On Android, apps like "PDF Merger" or "PDF Combine" from the Google Play Store work, though quality varies. For anything important, merging on a computer gives you more control and better visibility into what is happening to your files.