Definition
P90 usage is the 90th percentile usage level: 90% of customers use less, 10% use more.
Why it matters
P90 is a proxy for heavy usage. It helps you design tiers, overages, and limits that protect margin from power users.
Pricing implications
If your P90 usage is far above included limits, you need either higher overage rates or a higher base fee to avoid subsidizing heavy customers.
Measurement tips
Calculate P90 by plan or segment to avoid mixing different usage profiles.
Checklist
- Calculate P90 by plan and cohort.
- Compare P90 to P50 to understand usage skew.
- Use P90 to set tier breakpoints or overage rates.
- Recompute after major feature launches.
- Validate P90 with actual billing data.
- Keep the time window consistent (monthly is common).
- Avoid mixing free and paid users.
- Track P90 shifts after pricing changes.