How substantial should an extracurricular be to be impressive for t20 schools?

@PerryG gave a great response about quantifying your ECs as much as possible. Have you heard of the tiers of extracurriculars? They're much more granular in our chancing engine, but this post gives a more general breakdown: https://blog.collegevine.com/breaking-down-the-4-tiers-of-extracurricular-activities/. Generally, for top 20 schools, you want to have a couple tier 2 activities, and maybe even tier 1.

As for impact on the community, think about needs in your community and how your projects can address them. Is there a literacy problem in low-income communities? A lack of access to reading resources? A lack of writing ability and training? These seem like a couple needs that could be relevant to your projects.

Hope this helps, and best of luck!

I think no matter what your extracurricular activity is, quantifying your impact is the way you can demonstrate your EC's worthiness of consideration. Instead of just listing your activity and your role, focus on what you contributed to others or your recognition of greatness. What does that look like? STEM students have a unique position because there are many competition-based EC's that offer opportunities to win or place highly in State/National/International levels (think ISEF science fair). I could understand why you may feel its harder as a communication/writing spike, as gaining recognition is incredibly rare and difficult. Instead, I would try to demonstrate impact by highlighting how many people you "reached." If you are focusing on communication and the arts, isn't the number of people who willingly want to listen to what you have to say a good measure of how good your content is? In your case, you should try to quantify how many people have listened/subscribed to your podcast, you should quantify how many people participate in your club, quantify how many books you have sold (if it is successfully published). And people heavily underrate how important a large impact on your local community is; people always focus on a small accomplishment on a national level instead of directly changing the lives of people in your immediate reach. If you can organize a reading club at your local library for kids to instill an early appreciation for literature and have 25 kids show up regularly, then that is a pretty big impact that looks really good and is really important for your community. You have to be creative and make the opportunities for yourself, commit yourself to create really interesting and needed content, and document how many people you have "reached." In the practical sense, your impact on a community is much more important for society than you winning a certificate or trophy, and I think colleges are now catching on.