User Experience and Cognitive Engineering

On the Size of Font

November 18, 2007 · 5 Comments

Just back from SanFrancisco, I was trying to find an address in Montreal.
I had to slow down in order to read the street name. While slowing down, a car almost hit my back bumper! Hope it doesn’t sound familiar but I am sure it happens frequently.

Montreal street- Small street sign

On this Montreal picture, you can barely see the streets signs.

Montreal street names are poorly located and the font size is way too small.
How many car accidents happened as a result of this?
I wonder why city planners do not seem to known the law of font size.
n Montreal, this rule is violated everywhere: billboard signs, parking signs, print documents, etc.
How the heck can someone read the Montreal street signs?
What should be the font size for normal readability?
Angle for viewing font

The answer is: 2 X Tan (0.3 degrees/2) X reading distance

The angle that provides good readability for 95% of the people is 0.3 degrees. For a reader at a distance of 60 cm it results in a font size of 3 mm. For a reader at 50 meters, it is 25 cm or one foot. A good approximation is roughly 1/200 of the distance. Montreal city road planners should learn from SanFrancisco.

SanFrancisco Large street Name

On this picture, you can see there is a much bigger Mason street sign on a green background.
Note that this sign has been added over the small one.
The legibility rules are respected: Mix and San Serif fonts on green background and a size above one foot enough for 50 meters distance readability.

Categories: Cognitive Egonomics · Cognitive Engineering · Thomas Tullis · User Experience · cognitive ergonomics · cognitive group
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