Subscriber conversion rate

Studio reports subscribers gained per video, and dividing that by the video's views gives the rate. It answers a question watch time cannot: whether the video persuaded anyone to come back. Comparing the figure across two of your own videos is where it earns its keep, because everything else is held roughly constant. Comparing it against another channel's number, or against a benchmark table from a blog post, tells you close to nothing, since format, topic, video length and traffic source all move it independently. Build your own baseline over a dozen uploads and watch which ones beat it.