Match text size to viewing distance

Start with the screen’s apparent size

A phone held at arm’s length can look larger than a TV across a hall. What matters is how much of the reader’s view the letters occupy from the place where the message must work.

Use a phone for close personal communication, a tablet for a counter or small area, and a larger display or projector when the message must cross a room.

Shorten before reducing the type

Every extra character competes for the same screen width. Keep the identifying name, action, place, status, or number and remove context the reader already has.

For wide phrases on a phone, landscape orientation often allows larger letters. A single word or number may work better in portrait.

• Phone: nearby person or small counter
• Tablet: reception, table, or short room distance
• Laptop or TV: room, booth, or audience
• Projector: larger group after an on-site test

Use a real-world readability test

Stand at the farthest expected position, approach from the usual angle, and check the screen through any glass or crowd. Test daylight, dim light, and reflections when those conditions can change.

Ask someone who does not know the message to read it quickly. Their first answer is more useful than a theoretical font-size calculation.