Oh Dear report says most website outages are brief

Oh Dear has published a report on website uptime based on 1.8 million confirmed outages across 38,544 monitored sites. It found that most outages were brief, even though downtime affected a majority of sites.

The report analysed aggregate monitoring data collected between March and December 2025. During that period, 61.4% of monitored sites went down at least once. The average site recorded 47 separate outages, but half of all incidents were resolved in under two minutes and 98.6% were fixed within an hour.

That gap between typical incidents and a small number of extended failures shaped much of the analysis. The mean time to resolve an outage was 21.9 minutes, while the median was 1.9 minutes, showing how a small number of long disruptions pulled up the overall average.

Only 0.3% of outages lasted more than six hours. Although rare, those incidents pushed the average duration to more than 10 times the median, suggesting that headline uptime figures can mask the operational impact of a small number of severe episodes.

After hours

The timing of outages was another key finding. More than two-thirds, or 68%, began outside a standard 9-to-6 workday, on weeknights and weekends. The report estimated that this amounted to roughly 32 such incidents a year for the average monitored site.

The study also challenged how many teams interpret common uptime targets. A service running at 99.9% uptime would still be unavailable for nearly nine hours over a full year, a level that may sound minor in percentage terms but can still cause meaningful disruption for businesses that depend on websites and online services.

Mattias Geniar, Founder of Oh Dear, highlighted the difference between short incidents and longer failures.

"The number that surprised us wasn't how often sites go down, but the gap between the typical outage and the worst one. Half are over in under two minutes, but a small tail runs for hours, and that tail is where the real cost sits. Most teams build their alerting around the average outage. The data says build it around the rare bad one - and assume it starts at 2am, because two out of three of them do," said Mattias Geniar, Founder of Oh Dear.

Silent failures

Beyond outright downtime, the report pointed to faults that may not make a website appear offline. It found that 23.3% of monitored scheduled tasks, often known as cron jobs, failed or missed a run within a 30-day window.

These failures can include missed backups, unsent reports, and other back-end tasks that are essential to operations but invisible to most users. The findings also showed that 2.9% of sites had broken links and 0.7% of domains came within 10 days of expiring.

This means websites can continue to appear available while underlying systems are already failing. For smaller teams, especially those without dedicated around-the-clock operations staff, such issues can go unnoticed until they create a broader problem.

Geniar said these less visible disruptions often carry the highest cost.

"The outages people notice are only half the story. Nearly a quarter of the scheduled jobs we monitor failed or skipped a run in a single month - backups that quietly stopped, reports that never sent - and most teams don't find out until the day they actually need that backup. The most expensive failures are usually the ones that never trigger an alert," said Geniar.

Measured events

The report was based on measured monitoring telemetry rather than survey responses. It defined an outage as the period from the first failed uptime check to the first subsequent successful check, while excluding sub-minute disruptions.

Oh Dear monitors uptime, performance, broken links, mixed content, scheduled-task failures, and certificate expiry. The report argued that the practical challenge for web teams is less about eliminating every brief interruption than preparing for the smaller number of severe failures that arrive outside normal working hours.

The data covered 1,817,403 confirmed outages across 38,544 sites, with more than two-thirds of those incidents starting outside the working day.