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Viewing distance & text size calculator

Tell it how far away your farthest viewer stands and which screen you have. It tells you how big to set your text, in pixels and millimetres, and which screen size the room needs.

See how it works · 5 steps

Where your farthest guest stands

Start from the distance people read the screen from. Here: two metres, at the counter.

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From 2 m away, set text at least

38px

16.7 mm capital letters · 3.5 % of the screen's height · read at a glance

“Flat white £3.40” on a 55 inch screen, viewed from 2 m away

Flat white £3.40The smallest size someone who stops can still read

Flat white £3.4038 px minimum at 2 m

Magnified detail

Place

Plain view

Reception, lounge seating, a screen at eye level. The room is only a picture: it never changes a number.

What to set

Read at a glance: 38px
Smallest readable: 13px
Lines that fit at glance size: 21lines

Halve the distance to 1 m and 19 px is enough; double it to 4 m and you need 76 px. Letter height and distance move together, one for one.

Is the screen big enough?

Screen size for this room: 21″or larger
Picture area: 1217.6 × 684.9mm

AVIXA's 4/6/8 rule puts the farthest viewer within 8 picture heights. Below that, the screen is too small for the room whatever size the text is.

Before it goes up

Contrast: 13.01:1
Words: 3words

castv.ai's design review flags any text under 40 px on a 1920 px wide screen, and messages over 12 words. Set your brand pack's viewing distance to 2 m and every design is checked against this room.

Where these numbers come fromThe rules of thumb behind the answer

Sign makers’ rule of thumb: 1 inch of letter height for every 10 feet reads at a glance; 1 inch per 30 feet is about the limit for someone who stops to read.
Capital letters are about 70 % of the font size in the sans-serif faces signage uses, so the pixel sizes are font sizes.
Screen size: AVIXA’s 4/6/8 rule puts the farthest viewer within 8 picture heights.
Contrast: WCAG 4.5:1, the same check castv.ai's design review runs.
The room is drawn from just behind the viewer, so the screen is the size it looks from where they stand.

Photo: Hernan Santarelli · Pexels License. The window shows the real castv.ai tool, running on sample settings.

Where the answers come from

Sizes follow the sign makers' rule of thumb of 1 inch of letter height for every 10 feet for reading at a glance and 1 inch per 30 feet as the limit, with capitals about 70 % of the font size. The screen size uses AVIXA's 4/6/8 rule, and contrast the WCAG 4.5:1 ratio castv.ai’s design review checks.