HTTP Status Code Lookup
What each HTTP status code means, whether to retry it and whether it’s healthy.
Uptime & SLA Downtime Calculator
See how much downtime an SLA really allows, turn an outage into an uptime percentage, and work out the combined availability of services that depend on each other.
- Free
- No sign-up
- Runs in your browser
Uptime to allowed downtime
| Period | Allowed downtime | Required uptime |
|---|
Downtime to uptime
Services that all have to work
Downtime allowed by common SLAs
A month here is an average month (30.44 days) and a year is 365.25 days.
| Uptime | Per day | Per month | Per year |
|---|---|---|---|
| 99% | 14 min 24 s | 7 h 18 min 18 s | 3 d 15 h 39 min |
| 99.5% | 7 min 12 s | 3 h 39 min 9 s | 1 d 19 h 49 min |
| 99.9% | 1 min 26 s | 43 min 50 s | 8 h 45 min 58 s |
| 99.95% | 43.2 s | 21 min 55 s | 4 h 22 min 59 s |
| 99.99% | 8.6 s | 4 min 23 s | 52 min 36 s |
| 99.999% | 864 ms | 26.3 s | 5 min 16 s |
How to use the Uptime & SLA Calculator
- Enter an uptime percentage or choose a preset.
- Read the allowed downtime for each period.
- Or enter a downtime to get the uptime percentage.
- Add the SLAs of your dependencies to see the availability of the whole chain.
Never miss an expiry again
SensaCat watches SSL certificates, domain registrations and credentials, and reminds your team well before anything expires.
Frequently asked questions
About 1 minute 26 seconds per day, 43 minutes 50 seconds per month and 8 hours 46 minutes per year.
An SLI is a measurement, such as the percentage of successful requests. An SLO is your internal target for that measurement. An SLA is a contract with customers that sets a target and the consequences, such as service credits, if you miss it.
Multiply their availabilities. Two services at 99.9% that both have to work give 99.9% × 99.9% ≈ 99.8%, so a chain is always less available than its weakest part.
No. A service can pass its health checks while a background job, webhook or business process has quietly stopped. Monitor those flows as well as your endpoints.
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