Our talks are 30 minutes in length. Usually, this is 20-25 minutes of content followed by 5-10 minutes of Q+A. We've found this to be long enough for good detail while being short enough to hold the audience's attention. This length is also great for online -- just about the right duration for someone to watch during lunch or a coffee break.
If you intend to promote a product, app, service, or technology, be careful. It's important that your talk does not come across as a sales pitch. Consider giving a behind the scenes look at your work or take the audience on your journey that led to where you are now. Feature tours do not make good talks.
The best talks are focused on a personal experience. A great format for this is a three part story: