How to Merge Multiple PDFs into One

Prepare readable copies

Gather at least two PDFs and decide their final order. Use descriptive filenames so it is clear which document should come first. Keep the source files until the merged copy has been checked.

This task joins documents; it does not convert scanned pages into searchable text or remove password protection. A signed or interactive document needs a more careful check than a simple collection of pages.

Put the documents in order

1. Open Merge PDF and choose two or more PDFs.
2. Read the selected file list and use its ordering controls to arrange the documents.
3. Select Start processing and wait for the output or an error message.
4. Download the merged PDF and open it in a PDF viewer.

The screenshot shows a real local workflow in the English interface. Use the corresponding controls when the site language is Chinese.

Repeat the checked example

Download sample document A, which has two pages, and sample document B, which has one. Add A before B and merge them. Our downloaded result contained three pages; its page content streams matched A’s two pages followed by B’s page. These synthetic documents are supplied for checking the steps, not as a performance benchmark.

Check the boundaries between documents

Inspect the first page, the last page and each point where one source document meets the next. For simple PDFs that each contain a known number of pages, compare the output page count with their sum. Page count alone is not a sufficient check: the right count can still contain documents in the wrong order.

If you added the wrong file, change the selection and process again. Avoid repeatedly merging previously merged output when the original inputs are still available, because it becomes harder to tell which pages were already included.

If a file cannot be processed

Try opening that source PDF in a viewer. An encrypted or damaged document can fail even if another input works. Work from readable copies you are authorized to modify. Large documents can exceed browser memory; there is no site-wide size guarantee.

File processing takes place on this device. The browser may request application resources, which is different from uploading your selected PDF. More detail is available in Files, storage and processing.

When merging is the wrong first step

If a source includes pages you do not want, use Extract PDF Pages first and then merge the extracted copy. If your sources are photos rather than PDFs, create a PDF using Image to PDF before combining documents.