Alternate Mix PDF
Combine a fronts scan and a backs scan into one PDF in the right order, or interleave pages from any PDFs: one from A, one from B, and so on. Reverse the backs, check every page, then download.
A1, B1, A2, B2 … · in your browser · nothing uploaded
How to combine odd and even pages into one PDF
A scanner with a sheet feeder but no double-sided scanning gives you two files: one with the fronts (pages 1, 3, 5…) and one with the backs (pages 2, 4, 6…). To turn them into one PDF:
- Add the fronts file first, then the backs file. Use the arrows if they arrive the wrong way round: the file marked A supplies page 1.
- Tick Reverse on the backs file if you scanned the backs by turning the whole stack over. The next section explains why.
- Check the pages in the grid. Each tile shows its place in the new PDF and where it came from (A3 is page 3 of file A). Rotate or remove any page that needs it.
- Click Mix and download. You get one PDF named after the first file, ending in
-mixed.pdf.
Why the back pages come out in reverse order
When you turn the scanned stack over to feed the backs, the last sheet is now on top, so it goes through first. The backs file therefore starts with the back of the last sheet and ends with page 2. Mixing it as it is puts page 10 right after page 1. Reverse flips that file to 2, 4, 6… before mixing.
Example: a 5-sheet, double-sided letter (10 pages)
File A (fronts) holds pages 1, 3, 5, 7, 9. File B (backs, stack turned over) holds 10, 8, 6, 4, 2. With Reverse ticked on B and 1 page from each file in turn:
| Mixed PDF | Taken from | Letter page |
|---|---|---|
| Page 1 | A1 | 1 |
| Page 2 | B5 | 2 |
| Page 3 | A2 | 3 |
| Page 4 | B4 | 4 |
| Page 9 | A5 | 9 |
| Page 10 | B1 | 10 |
Result: pages 1 to 10 in order. Without Reverse you would get 1, 10, 3, 8, 5, 6, 7, 4, 9, 2. If you see that pattern in the grid, tick Reverse on the backs.
Some scanners and phone apps keep the backs in order (2, 4, 6…), for example if you re-sorted the stack before scanning. Then leave Reverse off. The page grid shows the result before you download, so you never have to guess.
Mixing more than two PDFs, or pages in blocks
| Setting | Mixed order |
|---|---|
| Two files, 1 page at a time | A1, B1, A2, B2, A3, B3… |
| Two files, 2 pages at a time | A1, A2, B1, B2, A3, A4… |
| Three files, 1 page at a time | A1, B1, C1, A2, B2, C2… |
| A has 3 pages, B has 2 | A1, B1, A2, B2, A3 |
Blocks of 2 or 3 suit files that come in sections, such as a two-page form in one PDF followed by its two-page answers in another. When one file runs out, the others carry on in turn, so no page is dropped.
Reverse works on any file, not only the second. Removing a page leaves the rest of the order alone. Its slot simply disappears, so fronts and backs stay paired.
What carries over to the mixed PDF
- Pages come over unchanged: text, images and scan quality stay exactly as they were. The pages are copied, not re-scanned or compressed.
- Bookmarks, form fields and the document title don't. The result is a new PDF built from the pages, so check it if the originals relied on these.
- Digital signatures are lost. A signature only covers the file it was made on.
- Locked PDFs can't be mixed. A file that needs a password to open or edit has to be unlocked first.
Once your pages are in order, you may want to add page numbers or delete blank pages left over from the scan.
Frequently asked questions
What does alternate mix mean for PDFs?
It merges PDFs by taking pages from each in turn (A1, B1, A2, B2…) instead of putting one whole file after the other. Its main use is rebuilding a double-sided document from a fronts scan and a backs scan.
Why is my mixed PDF in the wrong order?
Usually the backs file is reversed (it starts with the last page), or the files are the wrong way round. Tick Reverse on the backs and make sure the fronts file is A.
What if the fronts file has one more page than the backs?
That is normal when the last sheet has a blank back that the scanner skipped. The extra front page is added at the end, so the order still comes out right.
Are my PDFs uploaded?
No. The files are read, previewed and mixed in your browser, and the new PDF is saved straight to your device.
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