One of the questions I hear a lot from clients is, “How long should my video be?”

Here’s an interesting stat: The average length of a video on Facebook is 55.3 seconds, but the average view duration is 18.2 seconds.

It’s no secret that attention spans have gotten shorter. The proliferation of video on the web gives users a tremendous amount of choice, and has made them quite choosy. Research shows that more than 50% of viewers will tune out within the first six seconds of watching a video.

So, what does that mean to you? My standard advice is that a video should be as short as possible, but as long as necessary. But there are qualifications. A big one has to do with how targeted your audience is. For example, a patient seeking to understand her upcoming heart surgery is more likely to sit through a five-minute educational video about the procedure than, say, someone casually surfing the web who stumbles across a promotional video for a timeshare in Belize.

The current wisdom is that a general-audience web video should be a minute or less. And less can be a lot less. We’ve recently begun producing 15 second promos to run on Instagram.

For a more targeted audience, 2-3 minutes seems to be the upper limit unless you have a highly motivated viewer.

But what if you have a lot of information to convey? There’s a simple solution: Break it up into a series of shorter videos, each with a singular topic or focus.

If you host  your videos through YouTube (and that’s a smart thing to do,) you can take advantage of built-in analytics that provide very useful information about your video, like Watch Time and Average View Duration. You can use that info to compare performance of videos of different lengths, and determine the sweet spot for your particular audience.

And there are tricks to hook your viewers and hold them. For instance, videos that feature people in the opening moments are twice as likely to retain viewers.

Like so many things in life, the answer to “How long should it be,” is … It depends. I’ll be happy to talk through it with you and come up with an answer that’s right for you and your audience. (Thanks for taking the time to read this all the way through. You are a very motivated reader!)