The volume of referred purchases as a percentage of your total purchase. [1]
The global average referral rate is about 2.3%. If you already have product-market fit, happy customers and a steady stream of customers from your existing acquisition channels, you can expect to increase your sales by about 2% minimum. [2]
[1] Geter, T. What is Referral Rate? - eCommerce and Affiliate Marketing Blog. Retrieved May 21, 2021, from https://www.osiaffiliate.com/blog/referral-rate/
[2] Retrieved May 21, 2021, from https://www.referralcandy.com/blog/referral-rates/