Calculate 99.9%, 99.99%, and 99.999% uptime downtime instantly. See exactly how much downtime you're accepting with your SLA. No signup required.
About this calculator: Free SLA downtime calculator by PingView, an uptime monitoring platform. Industry-standard calculations aligned with AWS, Azure, and GCP methodologies. Last updated: December 2025. All calculations performed client-side for instant results.
Every minute of downtime costs money and trust. With PingView, you'll know the moment your site goes down - not hours later when customers complain.
An e-commerce site losing $1000/hour can afford $730/month in downtime. Most can't.
Most teams discover outages through customer complaints-often 15-30 minutes late. That's half your monthly SLA budget gone in one incident.
A single undetected outage can consume your entire month allowance.
Your monitoring frequency directly impacts how quickly you detect issues. Here's how different check intervals affect your SLA exposure:
Industry standard but risky for tight SLAs
• 5-10 min detection delay
• 11-23% of monthly budget per incident
• 2-3 incidents = SLA breach risk
Better balance for most applications
• 1-2 min detection delay
• 2-8% of monthly budget per incident
• More breathing room for fixes
Critical for mission-critical systems
• 30-60 sec detection delay
• Minimal SLA budget impact
• Fix issues before users notice
1-minute intervals with multi-location monitoring. Strike the perfect balance between cost and coverage.
With only 43m 12s of allowed downtime per month, every second counts. Get instant alerts before customers notice.
Start Monitoring FreeCompare different SLA tiers to understand the trade-offs between cost, complexity, and allowed downtime. Higher nines require exponentially more investment in infrastructure and monitoring.
| SLA Tier | Downtime/Year | Downtime/Month | Use Case | Typical Cost |
|---|---|---|---|---|
| 99%(Two nines) | 3.65 days | 7.2 hours | Internal tools, dev environments | $ |
| 99.9%(Three nines) | 8.75 hours | 43 minutes | Standard web apps, SaaS products | $$ |
| 99.95%(High availability) | 4.37 hours | 21 minutes | Business-critical apps, e-commerce | $$$ |
| 99.99%(Four nines) | 52 minutes | 4.3 minutes | Financial services, healthcare systems | $$$$ |
| 99.999%(Five nines) | 5.25 minutes | 26 seconds | Mission-critical infrastructure, telecom | $$$$$ |
Cost Reality Check: Each additional "nine" can increase infrastructure and operational costs by 3-10x. A 99.999% SLA might require redundant data centers, automated failover, 24/7 on-call teams, and extensive monitoring-significantly more expensive than 99.9%.
99.9% uptime means your service is available 99.9% of the time, which allows for approximately 8 hours and 45 minutes of downtime per year, or about 43 minutes per month.
This is often called "three nines" and is a common SLA target for standard web applications and services that aren't mission-critical but still require high availability.
SLA (Service Level Agreement): A formal contract between service provider and customer defining uptime guarantees and penalties for breaches. Example: "We guarantee 99.9% uptime or you get a credit."
SLO (Service Level Objective): Internal target set by the team, usually more stringent than the SLA. Example: Team targets 99.95% internally while promising 99.9% to customers.
SLI (Service Level Indicator): Actual measured metric used to track performance. Example: "HTTP requests with response time < 500ms" or "Successful API calls / Total API calls."
Each additional "nine" becomes exponentially more expensive to achieve and maintain.
Monitoring frequency directly impacts how quickly you detect and respond to outages. The faster you detect issues, the less of your SLA budget you consume.
Example: If you check every 5 minutes and your site goes down, you might not know for 5-10 minutes. That's 10-20% of your monthly 99.9% SLA budget (43 minutes) gone before you even start fixing the issue.
PingView checks as frequently as every 30 seconds, ensuring you know about problems before they significantly impact your SLA.
Your target should match your business criticality and customer expectations, not just industry averages.
Downtime % = (100 - Uptime %)
Allowed Downtime = Total Time × (Downtime % / 100)
For example, 99.9% uptime over a month (30 days):
• Downtime % = 100 - 99.9 = 0.1%
• Month = 30 days × 24 hours × 60 minutes = 43,200 minutes
• Allowed downtime = 43,200 × 0.001 = 43.2 minutes
Calculations assume 30-day months and 365-day years for consistency.