How to scan documents with your phone

I write these guides from the experience of preparing real filings, not as a lawyer or an immigration adviser. Every figure I quote links to its official source with the date I checked it. If something here is out of date, write to me and I will fix it.

You do not need a scanner. You need an official to be able to read the seal. Those are different things, and the second is achievable with a phone if you get four things right.

Use the phone's scanner, not the camera

Both systems ship with one and almost nobody uses it.

On iPhone, open Notes, tap the camera icon and choose Scan Documents. It is also in the Files app. On Android, open Google Drive, tap the plus button and choose Scan.

The difference is real. A scanner detects the edges, corrects the perspective so the page comes out rectangular, and gives you a PDF. A normal photo gives you a skewed sheet of paper lying on your desk.

The four things that decide legibility

1. Even light, never flash

Flash bounces off paper and burns out exactly the area where the seal usually sits. Find window light, or a lamp placed to the side. If your own shadow falls across the document, move, do not raise the brightness afterwards.

2. Flat paper, darker surface

A folded document casts shadows along the crease and confuses edge detection. Flatten it, and put it on a surface darker than the paper so the border is distinguishable.

3. Fill the frame

Every pixel spent on your table is a pixel not spent on the text. Get close enough that the document fills nearly the whole screen, with the phone parallel to the paper rather than at an angle.

4. Scan high, compress later

This is the rule most people get backwards. No tool recovers resolution that was never captured. You can reduce a sharp scan as many times as you like, but a bad scan is bad forever.

So capture at the maximum quality the phone offers, without worrying about weight, and adjust the size at the end, once you know the portal's actual limit.

Colour or black and white

Many applications explicitly require documents scanned in colour, particularly passports and identity documents. Black and white produces much lighter files, which is tempting when you are fighting a size limit, and it can invalidate the document outright.

If the application says nothing, stay in colour. If you are tight on space, reduce resolution before you drop colour.

If your iPhone produces HEIC files

It is the default photo format on iPhone and many portals do not accept it. You do not need to change your phone settings: drop the HEIC straight into this tool and it comes out as a correctly oriented PDF page.

Check before you send

Open it and zoom to 200 percent on the three areas a reviewer looks at: seals, signatures, and long numbers like a passport or reference number. If you have to squint, scan it again. It is faster than a requerimiento.

Common questions

Is a phone scan acceptable for an official application?

Yes, as long as it is legible, complete, straight and in colour when required. What gets rejected is illegibility, not the device that captured it.

How many DPI do I need?

Do not think in DPI while capturing. Fill the frame at maximum quality. As a reference, below roughly 115 effective DPI a seal starts to become unreadable.

How do I combine several pages into one PDF?

The phone scanner lets you add pages before saving. If they are already separate files, load them all here and use the merge option.