SLA Calculator - Uptime to Downtime

At 99.9% uptime, a 30-day month allows 43 minutes and 12 seconds of downtime. Enter your target and measurement period to calculate your budget, or compare common SLA levels below.

Allowed downtime43m 12sAt 99.9% uptime over 30 days, measured continuously, 24 hours a day.View 99.9% daily, weekly and average-year breakdown

Allowed downtime = period in seconds × (100 − uptime %) / 100. Displayed durations are rounded. Check your SLA for exclusions and measurement rules.

Compare common SLA targets

Compare the same period across targets. Choose a different month length above to update the budget column.

Allowed downtime by uptime target for 30 days and a 365-day year
Uptime target30-day budget365-day year
99%7h 12m3d 15h 36m
99.5%3h 36m1d 19h 48m
99.9%43m 12s8h 45m 36s
99.95%21m 36s4h 22m 48s
99.99%4m 19s52m 34s
99.999%26s5m 15s

Frequently Asked Questions

What does 99.9% uptime mean?

99.9% uptime allows 43 minutes and 12 seconds of downtime in a 30-day month, or 8 hours, 45 minutes and 36 seconds in a 365-day year. A monthly SLA must be met within each month; unused downtime does not automatically carry over.

How much downtime does 99.99% uptime allow?

99.99% uptime allows about 4 minutes and 19 seconds of downtime in a 30-day month, or 52 minutes and 34 seconds in a 365-day year. Results are rounded for display.

What's the difference between 99.9% and 99.99% uptime?

99.99% allows one tenth as much downtime as 99.9% over the same period. For a 30-day month, the unrounded budgets are 4.32 minutes and 43.2 minutes respectively.

How is uptime percentage calculated?

Uptime percentage = (total time minus downtime) / total time × 100. Use the same units for both times. For example, one hour of downtime in a 30-day month gives (720 − 1) / 720 × 100 = 99.8611% uptime.

Why do SLA calculators show different monthly downtime?

Some calculators use an average month instead of a calendar month. This calculator lets you choose 28, 29, 30 or 31 days. Our linked percentage breakdown pages use a 365.2425-day average year divided by 12 for monthly results. Choose the period specified in your SLA before comparing values.

Does this calculator prove SLA compliance?

No. It calculates a time-based downtime budget, not observed availability or service credits. Your agreement defines the measurement window, covered service, exclusions such as planned maintenance, and whether availability is measured by elapsed time or successful requests.

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      Software Architect at Atlassian
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