Why text messages are limited to 160 characters

Via marco:

Via Rocketboom:

Alone in a room in his home in Bonn, Germany, Friedhelm Hillebrand sat at his typewriter, tapping out random sentences and questions on a sheet of paper. As he went along, Hillebrand counted the number of letters, numbers, punctuation marks and spaces on the page. Each blurb ran on for a line or two and nearly always clocked in under 160 characters. That became Hillebrand’s magic number — and set the standard for one of today’s most popular forms of digital communication: text messaging. “This is perfectly sufficient,” he recalled thinking during that epiphany of 1985, when he was 45 years old. “Perfectly sufficient.”

While that’s a cute story that makes for a good article, it sounds like the real reason for the 160-character limit was more because the data channel’s packets had 128 bytes available for this sort of use and they restricted the character set (to a subset of 7-bit ASCII, I believe)

While the story may feel apocryphal, or even embellished, the typewriter exercise was crucial usability testing. Had someone not taken the time to count the number of characters in hundreds of messages, engineers would have simply said, “we can fit 128 ASCII characters in 128 bytes. Simple. Done. Next.”

It is very much like one of Andy Hertzfeld’s stories of the development of the original Macintosh at folklore.org. Bill Atkinson was developing drawing routines for QuickDraw and thought the functions for rounded rectangles would be too computationally intensive for the CPU. Steve Jobs wouldn’t hear it, insisting that “rectangles with rounded corners are everywhere!” He pressed the matter, taking Atkinson for a walk around the block pointing out every rounded rectangle he saw. It turns out that when Atkinson wrote the code, he was able to optimize it to the point that rounded rectangles drew almost as quickly as plain ones.

The point of this aside is that usability very often requires creative engineering solutions. When a system has certain hard limits, the trivial implementation imposes those limits directly on the user. Any creative limit pushing has a big impact on a product’s ease-of-use.