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How to scan documents with your phone
A good phone scan is readable, straight, and small enough to upload. Most of that is decided before you press the shutter. These are the habits that make the biggest difference, and how to turn the photos into a PDF that meets a size limit.
Before you take the photo
Light: daylight, no flash
Stand near a window during the day. Flash creates a bright glare spot and dark corners, and glare over a signature or a number makes it unreadable. Avoid standing between the light and the paper, or your own shadow falls on the page.
Background: contrast with the paper
Put white paper on a dark table, not on a white bedsheet. Contrast lets the camera, and any cropping tool, find the edges of the page cleanly.
Flatten it
Unfold creases and press curled pages flat, with a book on the edges if needed. A curved page gives curved lines of text that no app fully straightens.
Taking the photo
- Hold the phone flat above the pageParallel to the paper, straight above its centre. A tilted phone makes the page a trapezoid, with the far end smaller.
- Fill the frameGet close enough that the page almost touches the edges of the screen. More of the photo is document, less is table.
- Tap the page to focusWait a moment for the focus to settle, especially in lower light.
- Keep stillRest your elbows on the table. Blur from a moving hand is the most common reason a scan is rejected as unreadable.
- Check the photo before moving onZoom in on the smallest text. If you cannot read it on your phone, the person checking your form will not either.
Use the scanner your phone already has
Built-in scanners find the page edges, straighten the perspective and boost contrast automatically:
- Android: the Google Drive app has a Scan option under the + button, and many phones have a document mode in the camera app.
- iPhone: the Notes app has Scan Documents under the camera icon, and the Files app offers it too.
These scanners often save straight to PDF. If yours gives you photos instead, or you took ordinary photos, carry on with the next section.
From photos to one PDF
- Crop each photo to the paper edgesUse your gallery's crop tool. Removing the table around the page makes the file smaller and the page larger.
- Put the photos into one PDFOpen JPG to PDF, add the photos, put them in order, and keep A4 with a small margin for documents.
- Check the size, then compress if neededPhone photos are big; a single page is often 2–5 MB. Compress PDF with the limit your form gives. In our tests a 3-page A4 scan went from 4.54 MB to 164 KB under a 200 KB target.
Colour or black and white?
Many forms ask for colour copies of ID documents, because colour shows stamps, holograms and photos. For plain text documents, black and white is easier to read and compresses better. Phone scanner apps usually offer both; choose colour whenever in doubt, since you can always go smaller but cannot add colour back.
Front and back of an ID card
Portals often want both sides in one file. Photograph each side separately, then add both photos to JPG to PDF: the front becomes page 1 and the back page 2. If the portal wants an image instead of a PDF, check its instructions, and use Compress image to reach its size limit.
Common problems and fixes
| Problem | Cause | Fix |
|---|---|---|
| Bright patch on the page | Flash or a lamp reflecting | Turn off flash, move to daylight, tilt the page slightly away from the light |
| Text blurry only in one area | Focus was on another spot, or the page was curved | Flatten the page and tap to focus on the middle |
| Page looks like a trapezoid | Phone was tilted | Hold the phone parallel, or use the built-in scanner to straighten |
| PDF comes out sideways | Phone was held in landscape | Fix it with Rotate PDF |
| File far too big | Full-resolution photos | Crop tightly, then compress to the form's limit |