Poster font size: how big text must be to read from a distance

How do you calculate poster font size from viewing distance?

Start with the distance, not the font menu. Measure where people will actually stand or walk when they first notice the poster, then divide that distance in feet by 30. The result is the minimum height of a capital letter in inches. A reader 15 feet away needs capitals at least 0.5 inch tall, and a reader 30 feet away needs capitals at least 1 inch tall.

Converting that height into a point size takes one more step. There are 72 points in an inch, but the point size describes the whole body of the font, not the visible capital. In many typefaces the capital height is somewhere around two thirds to three quarters of the point size. If your chosen font has capitals that measure 70 percent of the point size, divide the capital height in points by 0.7. For the 15 foot example, 0.5 inch is 36 points of capital height, so you would set the line at about 51 points.

Because this conversion depends on the exact typeface, measure a printed capital with a ruler instead of trusting the number in the software. Two fonts at 60 points can differ by a surprising amount in visible height.

What font size chart works for common poster distances?

The table compares the road sign ratio with the stricter visual character heights in the ADA Standards for a sign mounted 40 to 70 inches above the floor. Point sizes assume capitals that are 70 percent of the point size.

The two columns answer different questions. The road sign ratio is a guideline for large, reflective, high contrast signs read by drivers. The ADA table adds 1/8 inch of height for every foot beyond 6 feet so that readers with low vision can read permanent signs. Promotional posters are generally not regulated by either rule, but the gap between them is a useful reminder: the minimum is rarely comfortable. If the poster must work for everyone who passes, plan toward the larger figure.

What is the minimum font size for body text on a poster?

Supporting details are read from a different place than the headline. A passerby notices the headline from across a room, then walks closer to read the date, address or offer. Size each layer for its own distance.

A simple way to plan is three tiers. The headline is sized for the approach distance. The key details, such as time, place and the next step, are sized for the spot where an interested person pauses, often 4 to 6 feet away, which calls for capitals of at least 0.17 to 0.2 inch by the road sign ratio. Fine print, such as terms, can be sized for arm's length. Anything a reader must have to act, like a date or a web address, belongs in the second tier, never in the fine print.

Does the typeface change how large the text looks?

Yes, often more than a few points of size. Wide letters with generous spacing and a tall x height read larger than condensed or decorative faces at the same point size. The ADA Standards describe the kind of lettering that stays legible: conventional forms without italic, script or highly decorative styles, a capital O between 55 and 110 percent as wide as the capital I is tall, and strokes between 10 and 30 percent of the height of the capital I.

Case matters too. The 2009 traffic sign manual sets lowercase letters at 3/4 of the height of the initial capital when mixed case is used. A condensed headline can fit more words, but a shorter headline in an open typeface usually reads faster.

How much contrast does poster text need?

Letters need a clear light on dark or dark on light relationship, and the ADA Standards also require a non glare finish for visual characters on the signs they cover. Thin, pale type over a photograph often fails even when the headline itself works. Place essential details on a plain panel of color and keep a consistent background behind each line.

Lighting and finish change contrast after printing. A glossy sheet under spotlights can hide a line of text behind a reflection, which is one reason to compare a matte or gloss finish for the room where the poster will hang.

How should you test poster text before printing?

A screen preview cannot show how text reads across a room. Print the headline and one line of details at actual size, even if you tile it across office sheets, and mount it at the planned height. Then walk to the approach distance in normal light.

• Print the real words at the real size, not placeholder text.
• Mount the test at the intended height and location.
• Read it from the approach distance and from the pause distance.
• Ask someone who has not seen the design to read it aloud.
• Check numbers, dates and web addresses separately from the headline.
• Enlarge or shorten anything that causes hesitation.

How does poster size limit how much text fits?

Once you know the letter height, the sheet width sets how many characters fit on a line. That is why the wording should be decided before the size. If a headline will not fit at a readable height, shorten the message before shrinking the type, or step up to one of the standard poster sizes that gives the line more room.

Keep type as vector text in the final export so edges stay crisp at any enlargement, and run the design through a poster print file checklist before ordering. If you want to try layouts quickly, the free poster maker previews your words on a poster layout before you prepare custom posters for print.