How to Scan Both Sides of a Document Into One PDF

An office printer with a duplex feeder scans both sides of a sheet in a single pass — but most of us hold two-sided documents in our hands in front of a phone. You do not need special hardware to get a clean two-sided PDF: capture both faces, keep the pairs in order, and save one combined file that reads front, back, front, back.

The two-pass method, done right

• Capture the front of the first sheet, then immediately the back of that same sheet, and keep repeating sheet by sheet. Adjacent pairs stay correct by construction.
• If you prefer batch passes, shoot all the fronts first and all the backs second — then reorder the stacks so every back sits right behind its front.
• Flipping a whole stack in a feeder reverses the order of the backs, which is exactly why re-viewing the sequence matters before you save.

Batch passes save repositioning time, but they reintroduce order problems. Sheet-by-sheet capture is the safest habit for a two-page form, an ID card, or any short document where order is the whole point.

Combine the sides into one PDF

1. 1Open the document scanner and capture each side as you go.
2. 2Use the reorder controls so the pages run front, back, front, back — never two fronts or two backs in a row.
3. 3Set a page size if your document needs one, then save and download the single PDF.

The preview panel is your safety net. When every second thumbnail is the same sheet with the writing flipped, the file is correct before it leaves your device.

What to do with long stacks

For a twenty-page job, capture the whole front stack, then the whole back stack, then interleave. With a phone that means flipping the document once as a block and shooting the reverse pass, exactly like a feeder would — then using the reorder view to weave the two stacks into one sequence. Spot-check page numbers or headers after interleaving, because a missed pair is easy to catch in the thumbnails and hard to spot in the final file.