Uptime nines converter
Convert an availability percentage into allowed downtime per day, week, month and year, or a month of downtime into availability.
How it works
Each extra nine cuts allowed downtime by ten times: 99.9% allows about 43 minutes a month, 99.99% about 4.
downtime = (1 − availability) × periodQuestions
How many nines do I need?
Match what users notice and what you can afford. Each extra nine usually costs far more than the last.
Does planned maintenance count?
It depends on your definition. Most SLOs count anything users see as down.