A while ago, I wondered about how often and in what way users really resize their browser windows, and set about finding out, only to get some dubious data that suggested my method was off. A (very late) second pass with a much better script for getting the data has yielded some more believable (and hopefully useful) numbers:
What is this telling us?
Over a 10 day test period, 8.5% of visits to the site included a resize of 50px or more in either dimension, and 3.66% included an orientation change (these will register a resize event as well, unless the viewport is almost square). That’s significant enough that we should keep it in mind when designing and developing fluid and responsive sites.
Also interesting is the difference between device types1, which shows that resizes are much less likely to occur on the desktop (where in turn the resize is much less likely to triggered by an orientation change), whilst the opposite is true with mobile, and tablets are roughly in the middle.
Update 15th April 2014: A kind reader ran the same test on the desktop version of a mainstream ecommerce site with over 1 million visitors per month and found that 2.03% of visits included a resize and 0.4% did an orientation change, which goes some way to validating these findings.
This is based on the grouping done automatically by Google Analytics with UA string detection. Imperfect, but still worth reporting on. ↩