Merging PDF files lets you combine separate documents into a single organized file — perfect for assembling reports, contracts, presentations, and more. Here is how to merge PDFs for free using any device.
When to Merge PDF Files
Merging PDFs is useful whenever you need to combine multiple separate documents into a single, organized file. Common use cases include combining multiple chapters of a book into one document, assembling a job application (CV + cover letter + certificates), creating a complete contract package from several individual agreements, and building a report that incorporates data from multiple spreadsheet exports.
A merged PDF is easier to send, easier for recipients to navigate, and presents as a more professional, complete document than a collection of separate attachments. Many submission portals and legal systems also specifically require documents to be submitted as a single PDF.
Method 1: Merge PDF Online (All Devices)
The simplest method for merging PDFs on any device is to use our free online Merge PDF tool. Upload your files, drag to reorder them, and download the merged result in seconds. No account, no watermarks, no software installation required.
The tool supports up to 20 PDF files per merge and individual files up to 50 MB each. All file formats are supported as long as they are valid PDF documents — including scanned PDFs, form-filled PDFs, and PDFs with embedded images.
This method works identically on Windows, macOS, iPhone, Android, and Chromebook — any device with a modern browser can use it.
Method 2: Merge PDFs on Mac Using Preview
macOS Preview has a built-in PDF merge feature. Open the first PDF in Preview, then go to View → Thumbnails to show the page panel. Drag additional PDF files directly into the thumbnail panel to add their pages to the current document. Drag individual page thumbnails to reorder them. Finally, save the merged file via File → Export as PDF.
This method is free, works offline, and gives you fine-grained control over individual page ordering — you can interleave pages from multiple PDFs rather than appending whole documents.
Note: on recent macOS versions, simply dragging a PDF onto Preview may open it as a new document instead of merging. Use the thumbnail panel drag method specifically to add pages to an existing open document.
How to Maintain Quality When Merging
Merging PDFs does not reduce quality — the tool combines the internal page streams from each document without re-encoding any content. Text, images, and vector graphics from each source PDF are preserved exactly as they were in the original files.
However, if the source PDFs use different fonts or color spaces, some rendering variations may occur in viewers that do not have the required fonts installed. For the most consistent output, merge PDFs that were created using the same software and settings.
After merging, if the combined file is very large, use our Compress PDF tool to reduce the file size without losing any visual quality.