How to Merge PDF Files — The Complete Guide (2026)

Merging PDF files is one of the most common document tasks. Whether you're combining invoices, contracts, or school assignments, there are several ways to do it. This guide covers the fastest and most secure methods available in 2026.

Method 1: Merge PDFs Online (Fastest)

The quickest way to merge PDFs is with an online tool. PDFably processes files entirely in your browser — nothing gets uploaded to any server, making it the most private option available.

1. Go to PDFably Merge PDF
2. Drag and drop your PDF files into the upload area
3. Rearrange files by dragging them into the order you want
4. Click "Merge PDFs" and download the combined file

The entire process takes seconds. No account, no signup, no file size limits.

Method 2: Using Preview on Mac

Mac users can merge PDFs using the built-in Preview app. Open the first PDF in Preview, show the thumbnail sidebar (View → Thumbnails), then drag additional PDFs into the sidebar at the position you want them. Save with File → Export as PDF. This method works well for a few files but becomes cumbersome with many documents.

Method 3: Using Adobe Acrobat

Adobe Acrobat Pro includes a Combine Files feature that merges PDFs with advanced options like bookmarks and headers. However, it requires a paid subscription starting at $19.99/month. For basic merging tasks, free tools like PDFably offer the same result at no cost.

Tips for Better PDF Merging

Name your files clearly before merging so you can identify them in the list. Use the A→Z sort feature if your files are already named in order. Check page counts to make sure you're including the right files. After merging, review the combined document to confirm everything looks correct.

Why Privacy Matters When Merging PDFs

Most online PDF tools upload your files to their servers for processing. This means your sensitive documents — contracts, financial records, personal information — pass through third-party infrastructure. PDFably takes a different approach by processing everything locally in your browser using JavaScript. Your files genuinely never leave your device.