SLA Calculator
Calculate uptime percentage and allowed downtime for your SLA
Calculate Your SLA
Common SLA Tiers
Industry-standard uptime guarantees and their allowed downtime
Basic
Entry-level service with minimal guarantees
Standard
Most common SLA for business services
Premium
High-availability services
Enterprise
Mission-critical systems
What is an SLA?
A Service Level Agreement (SLA) is a contract between a service provider and a customer that defines the level of service expected. It specifies metrics like uptime percentage, response time, and resolution time.
SLAs are critical for cloud services, web hosting, SaaS applications, and IT infrastructure. They provide accountability and set clear expectations for service quality.
The most common SLA metric is uptime percentage, which measures how much time a service is available and operational. For example, 99.9% uptime means the service can be down for up to 43.2 minutes per month.
How to Calculate SLA Uptime
Uptime Percentage Formula
Step 1: Define Time Period
Choose your measurement period: daily, weekly, monthly, quarterly, or yearly.
Step 2: Set Target Uptime
Determine your target uptime percentage (e.g., 99.9%, 99.99%, 99.999%).
Step 3: Calculate Downtime
Use the formula: Allowed Downtime = Total Time × (1 - Uptime %)
Step 4: Monitor Compliance
Track actual uptime and compare against your SLA target.
SLA Tiers Comparison
Understanding the difference between uptime percentages
| Uptime % | Daily Downtime | Weekly Downtime | Monthly Downtime | Yearly Downtime | Typical Use Case |
|---|---|---|---|---|---|
| 90% | 2.4 hours | 16.8 hours | 3 days | 36.5 days | Development/Testing |
| 95% | 1.2 hours | 8.4 hours | 1.5 days | 18.25 days | Internal Tools |
| 99% | 14.4 min | 1.68 hours | 7.2 hours | 3.65 days | Small Business |
| 99.9% | 1.44 min | 10.08 min | 43.2 min | 8.76 hours | Business Services |
| 99.99% | 8.64 sec | 1.01 min | 4.32 min | 52.56 min | E-commerce |
| 99.999% | 0.86 sec | 6.05 sec | 25.9 sec | 5.26 min | Mission-Critical |
SLA Best Practices
How to define and maintain effective SLAs
Set Realistic Targets
Don't promise 99.999% uptime if you can't deliver it. Start with achievable targets and improve over time. Consider your infrastructure, team capacity, and budget.
Define Clear Metrics
Specify exactly what counts as downtime. Include planned maintenance windows, measurement methods, and exclusions. Be transparent about how you calculate uptime.
Monitor Continuously
Use automated monitoring tools to track uptime 24/7. Set up alerts for incidents and maintain detailed logs. Real-time monitoring helps you catch issues before they breach SLA.
Communicate Proactively
Notify customers immediately when incidents occur. Provide status updates and estimated resolution times. Transparency builds trust even during outages.
Plan for Redundancy
Implement failover systems, load balancing, and backup infrastructure. High availability requires redundancy at every level: servers, networks, and data centers.
Review and Improve
Conduct post-incident reviews to identify root causes. Track SLA compliance trends and adjust processes. Continuous improvement is key to maintaining high uptime.