Scan a document to PDF

Use the scanner already in your pocket

Most phones ship a document scanner inside an app you already have. On iPhones it lives in Notes: open a note, tap the camera icon, choose Scan Documents, and the phone finds the page edges itself. On Android it lives in Google Drive behind the plus button and the Scan option. Both correct perspective, both write PDF directly.

Try the built-in scanner before anything else. It finds edges, flattens the perspective of a shot taken at a slight angle, and costs nothing. A plain photograph is the fallback, not the plan: it keeps every flaw of the moment instead of correcting them.

What separates a scan from a snapshot

A scan is flat, evenly lit, square to the page and cropped to the paper. A snapshot of a document is none of those, which is why an office rejects it. The difference is not resolution. It is geometry and light.

Put the sheet on a plain surface. Stand so the light comes from the side rather than from behind you, because your own shadow across the page is the single most common fault. Hold the phone parallel to the paper and fill the frame with the sheet.

Turn the flash off and leave it off. A flash blows out the centre of the page and leaves the edges dark, which no later step can even out. If the room is dim, move the paper closer to a window instead of reaching for the flash.

If you photograph the pages instead

A plain photograph works, with the same rules about light and angle. Shoot every sheet in order and do not stop halfway to check, because counting at the end is faster than working out later which of forty pictures is missing.

Watch the format. Recent iPhones save photographs as HEIC by default. Use HEIC to PDF for those files instead of converting them first.

Keep the camera app's HDR and live-photo extras off for documents. They add processing the scan does not need and occasionally smear fine print. The plainest photo setting gives the cleanest page.

Paper prep matters more than the app

Flatten the stack before you start. Fan curled pages the other way, press down the spine of a booklet with a second book, and remove staples rather than shooting around them. A scanner app corrects angles, not topography: a page that rises toward the spine stays blurry in the middle no matter which app takes the picture.

Clean the lens with your shirt. A fingerprint films over exactly the frequencies that small print lives at, and the result looks out of focus when it is only dirty. Thirty seconds of prep beats ten retakes.

Keeping forty pages in order

One page is photography. Forty pages is logistics. Shoot in fixed order, top of stack to bottom, and never reorder mid-shoot to retake a blurry page. Retakes go at the end in a second pass, marked by shooting your hand before and after so the bad pages are trivial to find and delete.

Count out loud as you shoot. Saying each page number keeps a rhythm that prevents skips, and the count at the end must match the stack. A forty-page scan with thirty-nine images is missing exactly one page, and finding it later means reshooting the whole middle.

Name the batch before you start, not after. A folder called scan becomes four folders called scan-2 within a week. Date plus subject, written once, saves every future search.

When the phone is not enough

Phones lose to real scanners in three situations. Bound books never lie flat, so the middle stays blurry no matter the app. Fragile paper risks tearing under handling. And large stacks turn a quick phone session into a long one with aching arms.

Use a flatbed for books and fragile sheets, an automatic feeder for stacks. Libraries, copy shops and offices have both, and one visit beats an afternoon of phone photography. What the phone wins is availability: the document in front of you right now beats the perfect scan next week.

Check before the paper leaves

Every scan should be verified against the paper while the paper is still there. Open the PDF, page through it on a bigger screen than the phone, and read at least the first and last line of every page. Blurry corners, cut-off edges and missing sheets are all trivial to fix by reshooting and painful to fix later.

Shred nothing until the check passes. The paper is the only backup until the scan is verified, and shredding first turns every missed page into a lost page. Keep the stack for a day, verify the file, then let the paper go.

Keep the verified file in two places from that moment on. A phone that holds the only copy of forty pages is one dropped phone away from a reshoot. Copy the finished PDF off the phone the same day you make it.