UPTIME MONITORING GUIDE

Uptime Percentage Explained

Uptime percentage is the share of successful checks during a measurement window. The number is useful only when you also understand the window, check frequency, and what counts as success.

Reading the number

At 99.9% monthly uptime, roughly 43 minutes of downtime can occur in a 30-day month. At 99%, the allowance is more than seven hours.

Measurement windows matter

A daily, weekly, and monthly percentage can tell different stories. Short windows highlight current incidents; longer windows show reliability trends.

Checks are samples

A monitor observes service at intervals. A ten-minute check can miss a short outage between requests, while one-minute checks provide a more detailed external record.

Key takeaways

  • Always state the measurement window.
  • Use shorter intervals for critical services.
  • Pair percentages with incident duration and impact.

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Put the guide into practice

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