How to Interleave PDF Pages — Alternate Pages from Two PDFs
Interleave pages from two PDFs to combine odd and even pages from double-sided scans. Free browser-based tool for alternating page merge.
Interleaving combines pages from two PDFs in alternating order: page 1 from PDF A, page 1 from PDF B, page 2 from PDF A, page 2 from PDF B. FixMyPDF's Merge tool can help — and here's the full workflow for double-sided scan assembly.
When You Need to Interleave PDFs
The most common use case: a double-sided document scanned on a single-sided scanner. You scan all odd pages (front sides) first, then flip the stack and scan all even pages (back sides) — producing two PDFs that need to be interleaved into one correctly ordered document.
The Double-Sided Scan Problem
Say your document has 20 pages. Scan A contains pages 1, 3, 5, 7 ... 19 (10 pages in order). Scan B contains pages 20, 18, 16, 14 ... 2 (10 pages in reverse order, because you flipped the stack). You need: A1, B10, A2, B9, A3, B8 ... alternating while reversing B.
Step 1: Reverse the Back-Side PDF
First, use Split PDF to confirm page count, then use Reorder Pages to reverse the order of the even-pages PDF (Scan B), so its pages run 2, 4, 6 ... 20 instead of 20, 18, 16 ... 2.
Step 2: Split Each PDF Into Individual Pages
Use Split PDF with "Split Every Page" option on both PDFs. This gives you individual page files: A_page1.pdf, A_page2.pdf ... and B_page1.pdf, B_page2.pdf ...
Step 3: Merge in Alternating Order
Use Merge PDF to combine pages in the correct interleaved order: A_page1, B_page1, A_page2, B_page2 ... Add files one by one in this alternating sequence and merge all at once.
Faster Alternative: pdftk on Mac/Linux
pdftk can interleave natively: pdftk A=odd.pdf B=even.pdf shuffle A B output interleaved.pdf. This handles the alternation automatically without manual page-by-page merging. For one-time GUI workflows on any platform, the FixMyPDF manual method works.
Verifying the Interleaved Result
After merging, open the result and scroll through checking that: odd pages have correct front-side content, even pages have correct back-side content, and numbering flows correctly throughout the document.
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