How to Merge PDF Files on Windows — 2026 Guide
Combine multiple PDF files into one document on Windows. Free and paid methods compared, including desktop tools, command-line options, and online services.
Why Merge PDFs?
Merging PDFs is one of those tasks that sounds trivial until you need to do it. You have five invoices that need to be submitted as one file. A report split across three documents needs to become a single PDF. Scanned pages saved as individual files need to be combined into one cohesive document.
Windows does not include a built-in PDF merge tool. You need third-party software or an online service. This guide covers the main options.
Methods for Merging PDFs on Windows
1. DalPDFMerge
Limits: Free version merges up to 3 files at a time. No watermark, no file size limit. Pro: $9.99 one-time
DalPDFMerge is a lightweight desktop tool focused on one task: combining PDF files quickly and reliably.
Key features:
- Drag-and-drop interface
- Reorder pages before merging
- Select specific page ranges from each file
- Batch merge multiple sets of files
- No file size limits
- No internet required — fully offline
The workflow is straightforward: add files, arrange them in the order you want, select pages if needed, and click Merge. The output is a single PDF with all content preserved.
Download DalPDFMerge free →
2. PDFtk (Command Line)
Limits: None (open source)
PDFtk is a command-line tool that can merge PDFs with a simple command:
pdftk file1.pdf file2.pdf file3.pdf cat output merged.pdfPros: Free, scriptable, fast, no GUI overhead Cons: Command-line only, must install separately, no visual reordering, no page range preview
3. Adobe Acrobat
Limits: Requires paid subscription ($12.99/month+)
Adobe Acrobat is the industry standard for PDF editing, and merging is one of its many features.
Pros: Full-featured, reliable, professional tool Cons: Expensive subscription, heavy software, overkill for just merging
4. Online PDF Merge Tools (Smallpdf, ILovePDF, etc.)
Limits: Free tiers with file size and daily limits
Web-based tools let you upload PDFs and download a merged result.
Pros: No installation, works on any OS Cons: Uploads files to external servers (privacy concern), file size limits, daily usage caps, requires internet, slower for large files
Comparison Table
| Feature | DalPDFMerge | PDFtk | Adobe Acrobat | Online Tools |
|---|---|---|---|---|
| Offline | Yes | Yes | Yes | No |
| Page reordering | Yes | Manual | Yes | Limited |
| Page range selection | Yes | Yes | Yes | Limited |
| Batch merge | Yes | Scriptable | Yes | No |
| Free version | 3-file limit | Full | No | Limited |
| Privacy | Local only | Local only | Local only | Cloud upload |
Tips for Better PDF Merging
- Check page orientation before merging — mixed landscape and portrait pages can look odd in the final document
- Verify page order — preview the arrangement before generating the output
- Consider file size — merging many high-resolution scanned pages can create very large files; compress afterward if needed
- Preserve bookmarks — some tools discard bookmarks and table-of-contents entries during merge
The Bottom Line
For occasional merging, DalPDFMerge handles the task quickly without subscriptions or cloud uploads. PDFtk is ideal for scripted or automated workflows. Adobe Acrobat makes sense only if you already pay for it. Online tools work in a pinch but come with privacy and size trade-offs.