How do I quantify the impact of Substack Notes on my newsletter?

I think there are a few stats I can look at. The first is the percentage of referrals on individual newsletter editions. Prior to last week, less than 1% of my referrals came from the Substack app. On last week’s two newsletters, that number jumped to between 3% and 4%. So app usage virtually tripled overnight.

The second stat to look at is the overall number of referrals coming from the Substack app. In the first 18 days of March, my newsletter received 439 referrals from the app. In the first 18 days of April, that number jumped to 1,115. That’s 150% growth.

The third stat to look at is the overall number of referrals coming from the Substack web domain. In the first 18 days of March, it was 168. So far this month it’s at 439, a jump of 161%.

If you add up Substack’s app and web domain referrals, it’s now the third biggest referrer to my newsletter behind “direct” and “Google” and it’s pretty close to being the second biggest referrer.