How to Interleave Two Scanned PDFs (Fronts and Backs)
Updated July 13, 2026
Without a duplex scanner, the usual workaround for scanning a double-sided document is two one-sided passes: scan every front, flip the whole stack, then scan every back. That leaves two files that need to be woven back into the right order before the document makes sense again.
Steps
- Add the first PDF — the fronts, or odd pages.
- Add the second PDF — the backs, or even pages — and tick reverse if they came out of the feeder last-page-first.
- Click Merge, then download the interleaved PDF.
Handling the flip
When you turn the stack over for the second pass, the feeder frequently reads it back to front, so the backs file ends up in reverse order relative to the fronts. Ticking the reverse option flips that second file before interleaving, so page one’s back lands right after page one’s front instead of at the wrong end of the document. If the two files come out with different lengths, the extra pages from the longer one are simply appended at the end.
Notes
Both files are processed locally, so nothing is uploaded. If you only need to join files end to end rather than weave them page by page, use Merge PDF instead. If a whole file just came out back-to-front, Reverse Pages is the simpler fix, and Organize PDF covers any manual reordering needed after that.