Other Calculators

Uptime Percentage Calculator

Calculate a service's uptime percentage and reliability "nines" rating from its total downtime over a given period.

Uptime percentage —

Reliability rating —

About the Uptime Percentage Calculator

Service reliability is commonly expressed as an uptime percentage over a billing period, often described informally in terms of "nines" — the number of 9s in the percentage. Higher nines correspond to dramatically less allowed downtime.

Formula: Uptime % = (1 − Downtime Minutes ÷ Total Minutes in Period) × 100, where Total Minutes = Days × 24 × 60

For reference, "three nines" (99.9%) allows about 43 minutes of downtime per month, while "five nines" (99.999%) allows only about 26 seconds — a common target in service-level agreements (SLAs) for critical infrastructure.