How much downtime does 99.9% uptime allow?
99.9% (three nines) uptime allows 8h 45m 36s of downtime per year. Here is the full budget, by period.
| Per day | 1m 26s |
| Per week | 10m 5s |
| Per month | 43m 12s |
| Per quarter | 2h 9m 36s |
| Per year | 8h 45m 36s |
Is 99.9% (three nines) the right target?
Three nines is the de facto standard SLA for most SaaS and B2B products — common enough that buyers treat it as table stakes. It signals a serious, production-grade service without the cost of the architecture that higher tiers demand.
What it takes to hold 99.9%
Multi-instance redundancy, health-checked deploys, fast alerting, and a basic on-call rotation. With only about 43 minutes of budget per month, detection speed and rollback discipline matter more than raw infrastructure.
Where you’ll see 99.9%
- A typical SaaS application dashboard
- A standard B2B product offering a 99.9% SLA
- A public API with paying developers
Each additional nine cuts the allowed downtime by roughly tenfold. The chart below shows where 99.9% sits relative to the other common uptime targets — and why detection speed, not just the headline percentage, decides whether you actually hold the line.
Frequently asked questions
- How much downtime is 99.9% uptime?
- 99.9% uptime allows about 8 hours 45 minutes per year — roughly 43 minutes per month, or about 1 minute 26 seconds per day. It is the most commonly promised SaaS SLA.
- Is 99.9% good enough for a SaaS SLA?
- For most SaaS and B2B products, yes — 99.9% is what buyers expect and what the majority of vendors publish. Payments, e-commerce checkout, and enterprise platforms usually need 99.99% or better.
- How do I monitor a service to 99.9%?
- With a 43-minute monthly budget, slow checks are a liability — a 5-minute interval can burn a tenth of your budget before it even notices. PingInsight checks as often as every second from three regions so breaches surface in seconds.
Compare every tier on the full uptime / SLA calculator, read what “three nines” really means, or see how 1-second uptime monitoring helps you stay inside this budget.
| Period | Allowed downtime |
|---|---|
| Per day | 1m 26s |
| Per week | 10m 5s |
| Per month | 43m 12s |
| Per quarter | 2h 9m 36s |
| Per year | 8h 45m 36s |
Detection matters as much as the budget. With 5-minute monitoring you can burn minutes of this allowance before you even detect an outage. PingInsight's true 1-second checks catch it almost immediately.
Back to the full uptime calculator or see how 1-second checks help you stay within budget.