How to merge PDFs and reduce the file size
For a predictable result, merge first and compress second. This locks in the page order and lets you apply one quality setting to the final document.
Recommended workflow
- Open every source PDF and remove duplicate, blank, or unwanted pages.
- Name files 01, 02, 03 in the order you want them to appear.
- Merge the PDFs and download the combined file.
- Open the merged file and verify page count, orientation, and readability.
- Compress the merged PDF, starting with the ebook preset.
- Check the final size and zoom into small text, signatures, and image details before sending.
Which compression preset should you use?
- screen: smallest output, suitable for on-screen reading when image detail is not critical.
- ebook: a practical starting point for email attachments and upload limits.
- printer: keeps more detail when the document may still be printed.
- prepress: favors quality, so the file-size reduction may be modest.
Why can a merged PDF become larger?
Merging preserves embedded images, fonts, and resources from the source documents. High-resolution scans can therefore make the result close to the sum of the original sizes, plus a small amount of document overhead.
What if the result is still over 5MB or 10MB?
- Remove unnecessary pages before merging, then compress again.
- Try ebook or screen instead of printer, and inspect the output after each attempt.
- Scanned documents usually offer more savings than text-only PDFs that were already optimized.
- If the destination accepts several files, split the document instead of making important text unreadable.
Privacy note
Avoid uploading highly sensitive documents to any online converter unless its processing and retention policy fits your requirements. PDF Tools removes processed files immediately when possible and runs fallback cleanup within about 10 minutes.