YouTube and some other video hosting websites now let you upload video clips that are up to 15 minutes in length but given the short attention span of Internet users, it is highly unlikely that people will stay with your video for that long.

So how long is too long for an online video?

Wistia, a video hosting service that also provides video tracking – like which parts of a video are popular with the online audience, when does their interest begin to fade and when do they quit watching a video altogether – has some interesting data to share in this regard.

Shorter is better

Wistia’s data suggest that shorter videos are more engaging that the longer ones and that people are more likely to watch the full video if it is short in length.

They found that 30-second video clips were viewed by 85% people all the way through while the completion rate was only 50% for videos that were between 2 to 10 minutes in length.

Wistia also suggests that you should consider putting the best stuff, the part that you want people to see, within the first 20 seconds of the video before they get distracted.

Related: Check my video screencasts on YouTube.