How to Merge PDF Files Step by Step
Quick Answer
To merge PDFs: open the PDF Merger, upload multiple PDF files, arrange them in the desired order, and click Merge. The tool combines the files into one PDF using a WASM-based library. All processing happens locally — your files are never uploaded.
Introduction
Merging PDF files combines multiple PDFs into a single document. This is useful for assembling reports from chapters, combining scanned pages, or creating a portfolio from separate documents. The merge operation concatenates pages in the order you specify. This guide shows you how to merge PDF files in your browser using a free online tool.
Step by Step
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Open the PDF Merger tool
Go to the PDF Merger tool page. The tool processes PDFs locally using a WASM-based PDF library (e.g., pdf-lib), so your files never leave your browser.
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Upload your PDF files
Click upload or drag-and-drop multiple PDF files onto the tool. You can select multiple files at once. The tool lists each file with its page count and size.
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Arrange the order
Drag the files to reorder them, or use up/down buttons. The files will be merged in the listed order — the top file becomes the first pages of the output.
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Merge the PDFs
Click Merge. The tool concatenates the pages from each PDF in order, producing a single combined PDF. This typically takes a few seconds for small to medium files.
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Download the merged PDF
Click Download to save the merged PDF. The tool shows the total page count and file size. Open the result to verify the order and content are correct.
Examples
Merge three chapter PDFs
Input: chapter1.pdf (5 pages), chapter2.pdf (8 pages), chapter3.pdf (6 pages)
Output: full-report.pdf (19 pages) — chapters in order
Merge scanned pages
Input: page1.pdf, page2.pdf, page3.pdf (1 page each)
Output: document.pdf (3 pages) — pages in order
Common Problems
- Wrong order —always verify the file order before merging. Drag to reorder if needed.
- Different page sizes —merging PDFs with different page sizes (e.g., A4 and Letter) produces a mixed-size document. This is usually fine but may look inconsistent.
- Encrypted PDFs cannot be merged —decrypt each PDF first (remove passwords) before merging.
- Large output files —merging many large PDFs can produce a very large output. Compress the result if needed.
Tips
- Arrange files in the correct order before merging —the top file in the list becomes the first pages.
- If you only need specific pages from a PDF, split it first, then merge the desired pages.
- Merge related documents into one for easier sharing —e.g., combine a cover letter, resume, and references into a single application PDF.
- Use our PDF Merger for private, browser-based processing —your files never leave your device.