Uptime
SLA calculator
Uptime Calculator
Convert SLA percentage to allowed downtime.
How to use ▸▾
Enter the SLA percentage (e.g. 99.9 for "three nines").
Results show maximum allowed downtime per year, month, week, and day.
Common SLAs: 99% = 3.65 days/year, 99.9% = 8.76 hours/year, 99.99% = 52.56 minutes/year.
—
—
—
—
How to use the Uptime tool
Service Level Agreements are usually expressed as uptime percentages like 99.9%, but percentages are abstract. This SLA calculator translates any uptime target into the maximum downtime you are allowed per year, month, week, and day — the numbers that matter when writing SLAs, planning maintenance windows, or comparing hosting providers.
- 1 Enter the SLA percentage, for example 99.9 for three nines.
- 2 Pick a preset like 99%, 99.9%, or 99.99% to compare common targets.
- 3 Read the allowed downtime per year, month, week, and day.
Example: Three nines: 99.9%
99.9
Per year: 8.8 hrs Per month: 43.8 min Per week: 10.1 min Per day: 1.4 min
Uptime FAQ
What is a good uptime percentage for a business?
99.9% (three nines) allows about 8.8 hours of downtime per year and is a common target for business websites. 99.99% allows 52.6 minutes per year and usually requires redundant infrastructure.
How much downtime does 99% allow?
99% allows about 3.65 days of downtime per year — roughly 7.3 hours per month. That is why aggressive nines (99.9%+) matter for production services.
How is downtime calculated?
A year has 525,600 minutes. Downtime = minutes in the period × (1 - SLA/100). The calculator does this for year, month, week, and day automatically.
Does uptime include scheduled maintenance?
It depends on the provider contract. Some SLAs exclude planned maintenance windows, others do not. Read the fine print before comparing providers on nines alone.
