A phone scan rejected by a bank portal is almost never the app’s fault. It is the angle of the shot, the light on the paper, or a resolution setting nobody checked.
Square the camera to the paper before you tap anything
Put the sheet on a surface that contrasts with it: white paper on a dark wooden desk, a pale receipt on a black folder. Glass tables are the worst case, because the scanner has to find the page edge against a reflection of the ceiling and often clips a corner.
Stand with the lens directly over the centre of the page, about 25–30 cm up for A4, and line the top edge of the phone up with the top edge of the paper. Brace both elbows on the desk. Avoid the one-handed shot from chest height with the screen tilted back: it turns a rectangle into a trapezoid the app then stretches back, and every stretch smears the letterforms that optical character recognition has to read.
Kill the flash: on coated or laminated paper it makes a white hotspot that wipes out a whole line. Use two lamps at roughly 45° to the page, one on each side, so no shadow falls across the sheet from your hands. And never shoot with a bright window behind the paper — the camera exposes for the window and the page goes grey.
Match the app mode to the job
Each of the big three scanner apps has a mode that crops and corrects perspective for you.
- Google Drive — tap the + button, then Scan. The shutter fires, four corner handles appear, and you drag them onto the page corners before tapping the tick. Add further pages with the + inside the preview so they land in one PDF rather than ten separate files.
- Apple Notes — new note, tap the camera icon, Scan Documents. Auto mode draws a yellow box and fires by itself when it detects edges; switch to Manual if it fires mid-shadow. After Keep Scan the pages sit in the note as a single PDF you can share straight to Files or Mail.
- Microsoft Lens — Document mode for a flat sheet, Whiteboard only for a whiteboard, since it crushes mid-tones and destroys photographs. It exports to PDF or Word, and the Word export keeps the text editable.
Do not use the normal camera app for typed pages. You get a 12-megapixel JPEG with sharpening halos around every letter, no edge detection, and no option to merge pages. It is the right tool only when the page carries something you want to keep looking like a photo — a stamp, a hologram, a handwritten sketch.
Pick resolution and colour for how the file will be used
Three settings cover nearly everything, and none is the default.
300 DPI, greyscale for anything you may reprint, archive or run through OCR. A single A4 page lands at roughly 300–600 KB in a compressed PDF. 150 DPI for email attachments and forms that only need to be legible on screen. Colour only when colour carries meaning: a highlighted clause, a red official stamp, a signature in blue ink. A colour A4 at 300 DPI is 2–4 MB, so a ten-page colour contract can pass 30 MB and bounce off Gmail’s 25 MB ceiling.
Keep multi-page documents as a single PDF rather than a folder of JPEGs — page order survives, and the text layer from OCR travels with it. If a portal insists on an image, export one page at a time as JPEG and keep it under 500 KB.
Name and file the scan so search can find it
Default names like Scan_20261030_1142.pdf are why people re-scan the same electricity bill three times. Use a date-first pattern, for example 2026-10-30_rent-receipt_landlord.pdf. Date-first means the folder sorts chronologically on its own, and the issuer name is the word you will actually remember in two years.
Put scans in one folder per document type — rent, medical, warranty, tax — inside Drive or iCloud Drive rather than on the phone’s internal storage. Drive runs OCR on uploaded PDFs and makes the text searchable, so searching “November” can surface the bill itself. On iOS, Notes scans are indexed by Spotlight, which makes Notes a decent inbox and a poor archive.
If storage is the constraint, move finished scans to the cloud and delete the local copy afterwards; the same housekeeping that applies to clearing out Google Drive prevents a 4 GB folder of utility bills. For getting the finished PDF onto a laptop without a cable, the methods in this phone-to-laptop transfer guide are quicker than emailing it to yourself.
Treat ID and medical scans as sensitive files
A black rectangle drawn in a markup tool covers pixels, which is fine for a JPEG. In a PDF the underlying text layer still contains the number, and anyone can select and copy it. Before sending a passport, national ID or insurance card, flatten the image or use a real redaction tool, then test it by trying to copy text out of the file.
Most portals want a straight-edged PDF under 2 MB at 300 DPI, or a JPEG under 500 KB. Crop to the document, not the desk, and send only the page that was asked for — a scan of the full booklet when the form wanted the photo page is a common reason for rejection. Apple’s iPhone support pages cover the Notes scanner, and Google documents the Drive scan flow at support.google.com/drive. If you are still deciding between the built-in apps and a dedicated scanner, this walkthrough of the 15-second method covers the trade-offs.