Pick a period and an availability target to see how much downtime it allows. Add the downtime you actually had to get your uptime percentage and whether you met the target. Plain arithmetic in your browser — nothing is sent anywhere.
A year is 365 days and a month is a twelfth of that (730 hours). Contracts that define a month as 30 days allow slightly less: 43 min 12 s at 99.9% instead of 43 min 48 s.
How much downtime is 99.9% uptime?
About 43 minutes a month, 10 minutes a week, or 8 hours 46 minutes a year. Each extra nine cuts the budget by ten: 99.99% allows roughly 4 minutes a month and 99.999% about 26 seconds. That is why the last nines are so expensive — at 99.999% a single slow deploy can use the whole month.
Why do calculators give slightly different numbers for a month?
Because “a month” is not a fixed length. Some use 30 days (720 hours), some the average month of a 365-day year (730 hours), and some 365.25 days to account for leap years. The differences are seconds to minutes; what matters is the definition in your contract, so pick the matching period above or enter the exact hours as a custom period.
Does scheduled maintenance count as downtime?
Only if the agreement says so. Many SLAs exclude announced maintenance windows, force majeure and outages caused by the customer, and measure availability per region or per service rather than overall. This calculator just does the arithmetic: subtract whatever your contract excludes before you enter the downtime.
Is this a HyperMonitors SLA?
No. This is a calculator, not a commitment: HyperMonitors is provided on a best-effort basis and no plan includes an uptime guarantee. What HyperMonitors can do is measure your own services and export an SLA report of their uptime.
Know your real uptime, not an estimate
The calculator is only as good as the downtime you feed it. HyperMonitors checks your sites and APIs from several regions, alerts you when they go down, and records every outage so the uptime figure comes from measurements. The free plan includes 5 monitors.
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