Updated 25 October 2026 · By the Upcertain team
Time to notice
An outage starts at a random moment between two checks. On average the next check comes half an interval later, at worst a whole interval later. Confirmation checks then add their own delay.
| Interval | Average time to the first failed check | Worst case |
|---|---|---|
| 30 s | 15 s | 30 s |
| 1 min | 30 s | 1 min |
| 5 min | 2 min 30 s | 5 min |
| 30 min | 15 min | 30 min |
Outages you never see
A check sees an outage only if it runs while the outage is happening. If an outage is shorter than the interval, whether any check lands inside it is a matter of chance:
| Outage length | Checked every 30 s | Every 1 min | Every 5 min | Every 30 min |
|---|---|---|---|---|
| 30 s | always | 1 in 2 | 1 in 10 | 1 in 60 |
| 1 min | always | always | 1 in 5 | 1 in 30 |
| 2 min | always | always | 2 in 5 | 1 in 15 |
| 5 min | always | always | always | 1 in 6 |
With a 5-minute interval, most 1- and 2-minute outages pass unnoticed. That can look like better uptime, but your users still saw the errors. If short outages matter, for example on a checkout or a login, use a short interval and let confirmation checks decide which failures are worth an alert.
Which interval for what
- 30 seconds: revenue paths, public APIs, login, anything with an SLA. You hear within about a minute.
- 1 minute: most production websites and internal tools people rely on during the day.
- 5 minutes: marketing pages, documentation, staging and side projects.
- 30 minutes to 24 hours: things that change slowly, such as a certificate on a rarely used host or a page you only need to know is still there.
What a short interval costs
- Load. One request every 30 seconds is 2,880 a day. That is nothing for most sites, but point the check at a lightweight health endpoint rather than a heavy page.
- Noise, without confirmation. More checks see more blips. Pair a short interval with one or more confirmation checks.
- Plan limits. In Upcertain the Basic plan checks as often as every 60 seconds; Team and Business as often as every 30 seconds. See pricing.
- Uptime targets. The faster you notice, the more of your downtime budget is left for fixing. At 99.9% a month allows 43 minutes in total; see what 99.9% uptime means.
Intervals available in Upcertain
30 seconds, 1 minute, 5 minutes, 30 minutes, 1 hour, 12 hours and 24 hours, set per monitor. Heartbeat monitors work the other way round: your job reports in, and you set how often it should.