Work out downtime minutes per year instantly with clear inputs, formula shown and shareable results.
Total annual downtime is planned plus unplanned minutes, and the year contains 525,600 minutes. Planned maintenance often dominates, which is why SLAs usually exclude it — and why zero-downtime deployment techniques deliver more measured availability than any amount of hardware redundancy.
Annual availability
downtime = planned windows x minutes + incidents x minutes; availability = 1 - downtime / 525600
Commercially it is usually excluded, but users experience it as downtime. Tracking both figures avoids a comfortable SLA number that does not match user perception.
Rolling upgrades, blue-green deployment and backwards-compatible schema migrations. All require the application to tolerate running two versions at once.