SLA math
99.9%
Three nines is the most common public SaaS target. It still allows nearly a full work day of downtime each year — planned or not.
- Per year
- 8.8 hours
- Per month
- 43.8 minutes
- Per day (avg)
- 1.4 minutes
8.8 hours a year is a full work day. Teams print three nines because it sounds high; the budget is still large enough that a bad afternoon does not blow the year. Spend it on real incidents, not on arguing about probe paths.
Who uses it
Who usually picks 99.9%
Typical for early B2B SaaS and marketing sites where a few hours a year is painful but survivable.
Caveats
Read this before you print it on a sales slide
- SLAs often exclude planned maintenance — read the fine print
- Customer-experienced downtime can exceed probe downtime (partial outages)
- A monthly error budget is easier to manage than an annual lump
FAQ
99.9% uptime, answered
Exact minutes for three nines, whether it is enough for SaaS, and what to publish instead of a higher number you cannot keep.
Keep reading
Nearby numbers
Turn outage minutes into dollars.
4.4 hours / year
53 minutes / year
Know the hours you actually have
Three nines is common. Measure it. Start free with minute checks from three regions — no credit card.