Percentage of revenue generated by the top customer, or top 20% sellers/suppliers. [1] [2]
A rule of thumb holds that if any single customer accounts for ten percent or more of your revenue or if your largest five customers account for 25% or more of revenue, you have a high customer concentration. [3]
[1] 34 Types of Startup Metrics to Measure (with Examples). Retrieved May 21, 2021, from https://startupdevkit.com/types-of-startup-kpis-metrics-to-measure-with-examples/
[2] Marketplace KPI Dashboard, https://versionone.vc/marketplace-kpi/
[3] Gateway Commercial Finance. Retrieved May 21, 2021, from https://gatewaycfs.com/bff/avoiding-high-customer-concentration