Collate scanned pages
Combine front and back scans from a two-pass scan into the right order.
or drop files here
Runs on your device — your files are not uploaded.
Free: files up to 200 MB, up to 50 files. No daily limit.
Collate scanned pages merges a scan of the fronts and a scan of the backs into one PDF in reading order, reversing the backs when your scanner fed them last page first.
How to collate scanned pages in 3 steps
- 1
Choose the PDF with the front sides and the PDF with the back sides.
- 2
Keep the backs-in-reverse preset selected.
- 3
Select Mix PDFs and download the collated PDF.
What can Collate scanned pages do?
- Runs in your browser: your files never leave your device.
- Made for scanners without a duplex feeder: scan the fronts, flip the stack, scan the backs.
- Backs are reversed automatically, since the stack is flipped.
- Pages end up in order: 1 front, 1 back, 2 front, 2 back.
- Different page counts: extra pages are appended at the end.
- Mode of Alternate & mix, so all its options are available.
How do I collate a PDF from a two-pass scan?
To collate a two-pass scan, add the fronts PDF and the backs PDF to Collate scanned pages, and the tool puts every back after its front. Many scanners can only scan one side of each sheet, so the usual workaround is to scan all the fronts, turn the stack over and scan all the backs. That leaves you with two PDFs, and the backs are in reverse order.
What does the backs-in-reverse preset do?
The preset reverses the backs file, then interleaves the two files so you get front 1, back 1, front 2, back 2, and so on.
What if the order looks wrong?
If pages are out of place, first check that both files have the same number of pages; extra pages are appended at the end. You can then fix single pages in Organize pages, and turn upside-down backs with Rotate PDF.
This is a mode of Alternate & mix. It runs on your device, and your files are not uploaded.
Frequently asked questions
How do I combine odd and even pages into one PDF?
Choose the file with the fronts (odd pages) first and the file with the backs (even pages) second, keep the backs-in-reverse preset and select Mix PDFs. Pages come out as front 1, back 1, front 2, back 2, and so on.
When do I need to collate scanned pages?
When your scanner only scans one side. You feed the stack once for the fronts, flip it over and feed it again for the backs, so the backs come out in reverse order.
Why are the backs reversed?
When you flip a stack over, the last sheet is on top. The preset reverses the backs file so each back follows its front.
What if the fronts and backs have different page counts?
The extra pages are added at the end, so the order will be off. Check that both scans have the same number of pages, including blank backs.
Is this the same as Alternate & mix?
Yes. It is a mode of that tool, opened with the fronts and backs preset.
Are my files uploaded when I collate scanned pages?
No. This tool runs in your browser, so your files stay on your device. Nothing is uploaded unless you choose to share the result or save it to a cloud drive.
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Last updated 23 October 2026