Cloud Tool

Uptime & Downtime Calculator

Turn an uptime percentage into real hours of downtime.

Free Tool No Registration Updated: Aug 10, 2026

How the calculation works

Downtime = (1 − uptime) × hours in the period. A 99.9% guarantee allows about 8.8 hours a year.

Frequently asked questions

Does the guarantee mean refunds?

Usually only a service credit. Read your provider’s terms.

Is planned maintenance included?

Often it is excluded from the guarantee.

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