Add two PDF files together

The short version

Open the two file page. Choose the document that comes first, then the one that comes second. The page shows both file names and their page counts so you can confirm you picked the right pair. Press merge and download the result.

Three files works the same way on the main merge tool, which takes any number of documents and lets you drag them into order. There is no difference in the engine, only in how much is on the screen.

Which one goes first

The order you set is the order you get. A cover letter followed by a CV means the cover letter is the first file. An invoice with its receipt attached means the invoice is first. The tool does not guess from file names or dates, which is deliberate: a guess that is right most of the time is worse than a rule you control.

If you get it wrong, do not rebuild the pair from scratch. Organize pages moves pages inside a document you already have.

What to check in the result

Open the merged file and look at three places: the first page, the join where the second document starts, and the last page. That is the whole check for a two file merge and it takes a few seconds.

The tool has already done the mechanical part. It read both sources, took a receipt of every page, then reopened the merged file and compared it page by page. The page count, the exact text of each page and every page width and height have to match, or the merge is refused instead of downloaded.

The two things that do not come across

Bookmarks and interactive form fields do not survive a merge, in this tool or in most others, because merging copies pages and those structures sit above the pages. If either of your two files carries them, the tool says so before it runs.

Document properties are cleared too, so the merged file carries no title, author or dates from either source. When you are joining your own cover letter to somebody else's template, that is usually the outcome you wanted anyway.

A password-protected PDF is refused outright. Remove the password first with a copy you are allowed to make, then merge.

When two files should stay two files

If the recipient needs to file the parts separately, or one of them gets updated on its own, send them as they are. Merging is for the case where one document is easier to handle than two, not a tidiness habit.

For a longer stack, or for scans and photos rather than PDFs, the full merging guide covers the order rules and what happens to bookmarks in detail, and the merge hub lists the rest of the cluster.

Merging on a phone

The tool runs in a mobile browser tab, so a phone does this as well as a laptop does. There is nothing to install and no account needed, and two ordinary documents are well inside what a phone can hold.

The ceiling is the memory a browser tab is allowed. On one measured device, an iPhone 16 Pro class handset, the tab was stopped at a hard 2 GiB limit with memory still free on the phone, so the limit is the browser's rule rather than the hardware running out. Two normal PDFs are nowhere near it. A pair of long photographed scans can be.