Do megapixels matter for document scanning?

Camera marketing counts megapixels; document legibility counts pixels per character — and technique controls that far more than the sensor spec sheet does.

The napkin math

An A4 page filling a 12 MP frame (~4000×3000) gets roughly 4000 pixels across 21 cm — about 19 px/mm, i.e. ~480 DPI equivalent: comfortably beyond flatbed office scans. Body text at 2 mm x-height gets ~38 px of height — crisp. The catch: that assumed filling the frame. Shoot the same page from twice as far and you've thrown away three-quarters of those pixels on tablecloth.

Where the pixels actually go

• Framing distance — the dominant factor, fully in your control.
• Focus and steadiness — a blurred 48 MP is a sharp 2 MP in a big file.
• Light — dim shots trade resolution for noise at the sensor level.
• Processing: ToPDF renders pages up to ~2400 px on the long side — beyond what text legibility needs, comfortably within what any modern phone supplies if framed well.

When more camera does help

Genuinely small originals with dense microtext (ID microprint, contract footnotes) benefit from newer sensors and real optical zoom — more honest pixels per stroke. For the other 95% of paperwork, the checklist beats an upgrade: any phone from the last several years scans office documents excellently when the six habits are followed.

Frequently asked questions

Should I enable my camera’s 48/108 MP high-res mode for documents?

Usually unnecessary — default binned modes are sharper in normal light and plenty for legibility. High-res modes shine on tripods in bright light; documents rarely need the ceremony.

Front camera in a pinch?

It works, at notably lower quality — front sensors are modest. Flip the phone; the 20 seconds are worth it for anything that matters.