A referral rate is the share of new customers in a period who came by referral. It is not the fee you pay the person who introduced them.
Referral rate equals the new customers who were introduced, divided by all new customers in the period.
Say 12 of 40 new customers in a month were introduced by someone. 12 divided by 40 is 0.30, so the referral rate for that month is 30 percent. Those counts are an example, not a benchmark.
Once you have your own rate, estimate what it is worth with the referral ROI calculator.
The number is only as good as the record of who introduced whom. If that record is a memory or a notes field, the rate is a guess.
A referral fee is the share of a deal you pay the person who made the introduction. A referral rate is the share of new customers who arrived that way. One can be high while the other is low.
When the question is what to pay, use the referral fee calculator.
A referral rate you can stand behind starts with a record of each introduction, not a reconstructed guess at the end of the month.