How to Merge PDF Files

When merging PDFs makes sense

Merging is useful when you have several related documents that need to travel as one file. Common situations include:

• Job applications: Combining a cover letter, resume, and portfolio into a single attachment instead of sending three separate files.
• Monthly reports: Bundling invoices, receipts, and statements into one packet for accounting.
• Study materials: Merging lecture slides, articles, and notes into a document that’s easier to print and search.
• Scanned documents: Combining individual page scans into one multi-page file.

How PDF merging actually works

A PDF file is essentially a container that holds pages along with instructions for displaying them. When you merge two PDFs, the process copies the pages from each source file into a new document in the order you specify.

The key point: merging does not re-render or re-encode the pages. The text, images, and formatting from each source page are preserved as-is. This means:

• Text stays selectable and searchable.
• Image quality is unchanged — no additional compression is applied.
• The process is fast because no heavy processing is involved.

What to watch out for

File size adds up

The merged file is roughly the sum of all source files. If you combine five 10 MB PDFs, expect a 50 MB result. If the final size matters — for email attachments or upload forms with size limits — compress the merged file afterward.

Page order is your responsibility

Most merge tools process files in the order you add them. If the final document needs to read in a specific sequence, arrange the files before merging. Some tools let you reorder files visually; others process them in the order they were selected.

Not everything carries over

A simple page merge typically does not preserve interactive elements like:

• Bookmarks and internal links
• Form fields
• Embedded multimedia

If your source PDFs rely on these features, test the merged output to make sure nothing important was lost.

Step-by-step: merging PDFs in your browser

1. Open the merge tool and add your PDF files — drag and drop or browse to select them.
2. Arrange the order so pages appear in the sequence you want in the final document.
3. Merge and download the combined file. The process happens locally in your browser, so there’s no upload wait.

When merging isn’t the right tool

If you only need a few specific pages from a larger document, splitting first and then merging the relevant parts gives you more control. If your source is a scanned image rather than a text-based PDF, the merged result will also be image-based — consider running OCR afterward if you need searchable text.

How to merge PDFs step by step

Use the Merge PDF tool when you want one readable file instead of a folder full of separate documents. Add at least two PDFs, arrange them in reading order, and download the result.

1. Open the Merge PDF tool.
2. Add two or more PDF files, each no larger than 20 MB.
3. Drag the file rows into the order you want; the order on screen becomes the page order.
4. Select the merge button and download merged.pdf.

Supported inputs and practical limits

The current tool accepts PDF files, up to 20 files per merge and up to 20 MB per file. It copies pages into a new PDF, so the practical ceiling also depends on your device’s available memory. A very large combined document can be slower or fail even when each individual file is under the upload limit.

Password-protected PDFs need to be unlocked first. Bookmarks, internal links, and form fields are not carried over by this page-merging workflow, so check the downloaded result if those features matter.

Privacy and troubleshooting

Files are read and combined in your browser; they are not uploaded to a Codrenix server. If a file is rejected, check its size and format. If merging fails, remove the problematic file and try smaller batches. If the page order is wrong, reset the list and drag each row into position before merging again.

For a large final file, follow the merge with ourPDF compressor, or useSplit PDF when you only need a subset of pages.