I have 35 PDFs but the merge tool only takes 20 at a time. How do I combine them all?

Why the limit is 20 files

Every file you add to Merge PDFs is opened and held in your device's memory until you merge, because the work happens in the browser rather than on a server. That is why the list has a tested limit of 20 files. If you select 35 at once, the tool takes the first 20 and tells you the rest were ignored, so do not assume everything went in.

Two rounds, step by step

1. Sort the files in your folder first and split them into a group of 20 and a group of 15.
2. Add the first group, check the order, then press 'Merge and download'.
3. Rename merged.pdf to something like part-one.pdf, so it cannot be confused with the final file, which will get the same default name.
4. Press 'Reset' to clear the list, then add part-one.pdf first, followed by the 15 remaining files.
5. Check that part one sits in position 1 and press 'Merge and download' again.

The limit batching does not get around

Rounds solve the file count, not the page ceiling. Each input can have up to 500 pages and the final merged document up to 2000. If your 35 files are long reports, you may hit the page ceiling before you ever need a third round, and two volumes will serve you better than one enormous file.

One small catch: if part one is itself over 500 pages, the tool will not accept it as an input in round two. Make the first batch smaller in that case, or keep two separate volumes.

• Merging in rounds does not reduce quality; pages are copied unchanged every time.
• On a phone, smaller batches are gentler on memory than a list of twenty large files.
• Delete the intermediate part-one.pdf once you have checked the final file.