What "99.9% Uptime" Actually Means (The Math)

Hosts love advertising uptime percentages. Let us translate them into something meaningful: minutes of downtime per year.

The math

• 99% = 3.65 days of downtime/year. Terrible.
• 99.9% = 8.77 hours/year. The industry standard.
• 99.95% = 4.38 hours/year. Good.
• 99.99% = 52.6 minutes/year. Excellent — and expensive.

What to look for in an SLA

A number without consequences is marketing. A real SLA specifies service credits — e.g. "10% credit for every hour below 99.9%." Ask what happens when they miss, not just what they promise.

Planned vs unplanned

Most SLAs exclude scheduled maintenance. That is reasonable — but the maintenance windows should be announced in advance and happen at low-traffic hours.

Our take: 99.9% with honest credits beats 99.99% with fine-print exclusions, every time.