PDF Merger: How to Combine Multiple PDFs
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Combining multiple PDF files into one is an everyday task for anyone working with documents. Merging a cover letter with a CV, combining monthly reports into a quarterly summary, assembling a contract with its attachments, or collecting scanned pages into one document — all require a PDF merger. The process is simple but requires the right tool to handle file ordering, page consistency, and output quality.
What a PDF Merger Does
The PDF Merger takes two or more PDF files and concatenates them into a single PDF. The output contains all the pages from all the input files, in the order you specify. All content — text, images, forms, bookmarks — from each source file is preserved in the merged output.
Step-by-Step: Merging PDFs
- Upload your PDF files. Select all files you want to merge. You can select multiple files at once.
- Reorder if needed. Drag to reorder the files into the sequence you want. The first file in the list becomes the first section of the output.
- Merge. Click Merge. The tool concatenates the files in order.
- Download the merged PDF. The output is a single PDF containing all pages from all input files.
Pro tip: If you need to merge specific pages rather than entire files, use the PDF Splitter first to extract the pages you need, then merge the extracted pages.
Common Use Cases
Assembling Application Packages
Job applications, visa applications, and grant submissions often require multiple documents in one PDF. Merge cover letter, CV, certificates, and references into a single submission file.
Combining Reports
Merge monthly reports into quarterly summaries, or combine department reports into a single company-wide document for board presentations.
Contracts with Attachments
Contracts often have multiple exhibits, schedules, or attachments that need to travel with the main document. Merge all parts into one PDF to ensure nothing gets separated.
Scanned Document Assembly
Scanning a multi-page document one page at a time (common with flatbed scanners) produces individual PDFs. Merge them into a single document in the correct page order.
Portfolio and Presentation Packs
Merge design samples, case studies, and client work into a single portfolio PDF for client or employer presentations.
Tips and Best Practices
- Consistent page sizes. PDFs with different page sizes (e.g., A4 and Letter, or portrait and landscape mixed) will merge with the mixed sizes preserved. If a uniform page size is important, normalise pages before merging.
- Page count before and after. After merging, verify the output page count equals the sum of all input page counts. This confirms no pages were dropped.
- Bookmarks and table of contents. Merging PDFs does not automatically create a combined table of contents. If you need navigation bookmarks in the output, you may need to add them manually in a PDF editor after merging.
- File size. The merged PDF will be approximately the sum of the input file sizes. If the result is very large, consider compressing it with the PDF Compressor afterwards.
- Password-protected PDFs. You need to unlock (decrypt) password-protected PDFs before merging them. The merger cannot process encrypted files.
Frequently Asked Questions
Is there a limit to how many PDFs I can merge?
Browser-based mergers typically handle up to 20-30 files comfortably. Very large numbers of files or very large individual files may be better handled by a desktop tool like PDFsam or Adobe Acrobat.
Will the merged PDF be searchable?
Yes — if the source PDFs contained selectable text, the merged PDF will be fully searchable. If any source PDFs were scanned images without OCR, those sections will not be searchable.
Can I merge PDFs with different orientations?
Yes — portrait and landscape pages merge correctly. Each page maintains its own orientation in the output.
Does merging PDFs affect the quality of images inside them?
No — a PDF merger concatenates the PDF structure without re-encoding content. Images, fonts, and all content are preserved at their original quality.
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Further reading: Mozilla PDF.js