PDF Merger
Upload or drag PDF files to merge them into a single document. Reorder pages by dragging the thumbnail grid before merging.
PDF Merger
Drag PDFs here or click to browse
Click or drag PDFs here
Merged PDF combines all pages from input files in the order they are arranged. No page limits, no file size limits (limited only by browser storage capacity).
How PDF Merging Works
PDF merging is performed entirely in your browser using the File API and PDF.js library. The process:
1. Each selected PDF is read as an ArrayBuffer 2. PDF.js parses the document structure and extracts page count 3. A new PDF is canvas-rendered by combining pages in the specified order 4. The resulting PDF is generated as a downloadable Blob
**Key points:** - All processing happens on your device - no files are uploaded to a server - Page order is user-defined via the drag interface - File size is limited only by your browser's storage capacity (typically 50MB-1GB per file depending on browser) - No account required, no software installation needed
- 100% private - files never leave your browser
- No upload to servers - complete privacy
- Works on any device with a modern browser
- Merge as many files as your browser can handle
Worked Example
Example: Merging three PDFs:
File 1: 'report-cover.pdf' (3 pages) File 2: 'report-ch1.pdf' (12 pages) File 3: 'report-ch2.pdf' (8 pages)
If merged in order 1→2→3: Result has 23 pages in order [cover, ch1 pages, ch2 pages]
If reordered to 3→1→2: Result has 23 pages in order [ch2 pages, cover, ch1 pages]
The calculator shows a thumbnail preview so you can visually confirm the order before merging.
Privacy & Security
- All PDF processing occurs in your browser using JavaScript - No input PDFs are transmitted to any server - No data about your documents is collected or stored - The merged PDF is generated as a local Blob and downloaded to your device - For sensitive documents, this browser-based approach is more secure than online PDF tools that require upload
Related Calculators
PDF Splitter
Extract specific pages from a PDF or split into separate files.
Open calculator →PDF Compressor
Reduce PDF file size with quality settings, see before/after size display.
Open calculator →PDF to Word Converter
Convert PDF documents to editable Microsoft Word format (.docx).
Open calculator →PDF to JPG Converter
Convert PDF pages to JPG images, with DPI and quality selection.
Open calculator →Frequently Asked Questions
Is there a limit on how many PDFs I can merge?
The limit depends on your browser's storage capacity. Most modern browsers can handle 10-20 moderate-size PDFs (up to ~100MB total). Very large PDFs or very many files may be limited by available memory.
Do I need to install anything to merge PDFs?
No. This PDF merger runs entirely in your modern web browser. No software installation, plugin, or account required.
Are my PDFs uploaded to a server?
No. This is a 100% client-side tool. Your PDFs are processed entirely in your browser and are never uploaded or sent anywhere.
Looking for a different calculator?
CalculatorPlus has free tools across finance, construction, math, health and more — each one showing the formula and a worked example.