Merge Odd and Even Pages: Combine Front and Back Scans
Scanned the fronts and the backs of a stack separately? Combine the two PDFs into one with the pages in the right order, even when the backs were scanned in reverse.
Most tools never upload your files
How to combine front and back scans into one PDF
To merge odd and even pages of a PDF into one file, add the two scans below and press Mix pages. Many office scanners and home printers have a document feeder but cannot scan both sides of a sheet. The usual workaround is to scan the stack twice: once for the front sides and once, after turning the stack over, for the back sides. That leaves you with two PDFs, one with the odd pages and one with the even pages, and usually the second one is in reverse order. Merge odd and even pages weaves the two files together page by page so the final PDF reads 1, 2, 3, 4 in the right order. It is free, needs no account and runs in your browser.
How to combine front and back scans into one PDF
- Scan the fronts. Put the stack in the feeder and scan it to a PDF.
- Scan the backs. Turn the whole stack over, put it back in the feeder and scan again.
- Add both PDFs here, the fronts file first and the backs file second.
- Leave "Back sides were scanned last page first" on if you flipped the stack, which is the normal case. Turn it off only if your backs PDF is already in order.
- Mix and download. The result shows the total page count so you can check nothing is missing.
Example with a 3 sheet stack
| File | Pages as scanned |
|---|---|
| Fronts PDF | 1, 3, 5 |
| Backs PDF (stack flipped) | 6, 4, 2 |
| Result | 1, 2, 3, 4, 5, 6 |
Tips for clean double sided scans
- Fan the paper before scanning so the feeder does not pull two sheets at once. A skipped sheet shifts every page after it.
- Keep the stack in the same orientation for both passes, only turn it over.
- Check page counts. Both files should have the same number of pages unless the last sheet is single sided.
- Fix upside down pages with Rotate PDF, and remove blank backs with Delete PDF Pages.
- Scanning with a phone? Scan to PDF lets you capture pages in any order and save one file.
Mixing versus merging
Merge PDF puts files one after the other: all pages of file one, then all pages of file two. This tool alternates between the files instead, taking one page from each in turn, which is exactly what two separate scan passes need. To rearrange pages by hand afterwards, use Organize PDF.
Private and lossless
The pages are copied as they are, without re-rendering, so scan quality and any text layer from OCR are kept. Everything happens on your own device: nothing is uploaded, stored or watermarked.
Who needs to merge odd and even pages
Home users scan tax papers, medical records and school forms on all-in-one printers that only scan one side. Small offices digitize signed contracts printed on both sides. Archivists and genealogists scan letters and old documents with writing on the back. In every case, two quick passes through the feeder plus this tool are much faster than placing every sheet on the glass twice.
Features
- Interleaves two PDFs: page 1 of the fronts, page 1 of the backs, page 2 of the fronts and so on
- Reverses the back sides automatically when the stack was flipped to scan them
- Works when one file has an extra page, for example a last page with a blank back
- Keeps text, links and image quality exactly as scanned
- Ideal for scanners with a feeder but no duplex scanning
- Runs in your browser: your documents are never uploaded
Frequently asked questions
When do I need this tool?
When your scanner's document feeder only scans one side. You scan the whole stack once for the fronts, flip it, and scan it again for the backs. You end up with two PDFs that need to be woven together: front 1, back 1, front 2, back 2 and so on.
What does "scanned last page first" mean?
When you flip the stack over to scan the backs, the feeder reads the back of the last sheet first. So the second PDF is in reverse order. With the option on (the default), the tool reverses it before mixing, so the result is correct.
Which file goes first?
Add the fronts scan first and the backs scan second. If you add them the other way round, simply remove them and add them again in the right order.
The two files have a different number of pages. Is that a problem?
No. When one file runs out, the remaining pages of the other are added at the end. Check the result if a sheet was skipped by the feeder, because pages after it will be shifted.
Some back pages are upside down. How do I fix that?
Rotate the affected pages with Rotate PDF after mixing. Some scanners flip the back side image, depending on how the stack was turned over.
Is my scan uploaded?
No. The pages are combined by your browser on your own computer.