Uptime SLA Calculator
Compute allowed downtime per period for 99%–99.999% SLAs.
What does an SLA like “99.9% availability” actually allow in downtime? Enter a target availability (%) and this calculator converts it into the maximum allowed downtime per day, week, month, quarter and year.
Use it to design SLAs, compare cloud/hosting guarantees, or judge whether an outage breached a contract.
Allowed downtime at 99.9% availability
| Day | 1m 26s |
|---|---|
| Week | 10m 5s |
| Month (30d) | 43m 12s |
| Quarter (90d) | 2h 9m 36s |
| Year (365d) | 8h 45m 36s |
The meaning of "nines"
Availability is often counted in "nines." Each extra nine cuts allowed downtime by roughly 10×.
- 99%: ~3.65 days/year
- 99.9%: ~8.76 hours/year
- 99.99%: ~52.6 minutes/year
- 99.999%: ~5.26 minutes/year
Frequently asked questions
Is scheduled maintenance counted as downtime?
It depends on the contract. Pre-announced maintenance is often excluded, so check the 'scheduled maintenance' clause.
How many days is a month here?
This tool uses 30 days. Real SLAs may use calendar months or a fixed 30-day basis.
What happens if the SLA is missed?
Most providers offer service credits. These are often claim-based rather than automatic, so check the terms.
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