YouTube scripts vary a lot in length as some YouTube videos are just a couple of minutes long and others might last an hour or more. If you’re aiming for a 10 minute video, that’s around 1,500–2,500 words, depending on how fast you talk.
With outline scripts, you don’t need every word for your video. Instead, you’ll need an introduction, conclusion, and around 3–7 key points. You can then speak about each point for 1–2 minutes.
There’s no “right” length for a YouTube video, but recent statistics suggest that videos around 7–15 minutes long perform best. You’ll want to think about your own audience and channels similar to yours, and see what lengths of videos seem popular.