99% Uptime Downtime Calculator & SLA Allowance (Two Nines)
A 99% availability level ("Two Nines") permits up to 7 hours and 18 minutes of downtime per month, or more than 3.6 days across a year. It is suitable for internal tooling, staging environments, batch processing pipelines, or free-tier services.
99% Maximum Allowed Downtime by Time Window
Exact permissible service unavailability before breaching the 99% SLA target.
864s per 24 hours
6048s per 7 days
26298s per billing month
315576s per 365.25 days
Calendar Month Length Variance for 99% SLA
Contractual downtime allowances vary based on the number of calendar days in the billing period.
| Month Duration | Total Time Available | Max Allowed Downtime | Downtime in Seconds |
|---|---|---|---|
| 28 Days (February Common) | 2,419,200 sec (672 hrs) | 6h 43m 12s | 24192s |
| 30 Days (Apr, Jun, Sep, Nov) | 2,592,000 sec (720 hrs) | 7h 12m 0s | 25920s |
| 31 Days (Jan, Mar, May, Jul, Aug, Oct, Dec) | 2,678,400 sec (744 hrs) | 7h 26m 24s | 26784s |
| Standard Average Month (30.4375 Days) | 2,629,800 sec (730.5 hrs) | 7h 18m 18s | 26298s |
Comparing 99% Against the Table of Nines
Understand how each additional "nine" reduces allowable downtime by an order of magnitude (10x).
| Availability Tier | SRE Classification | Daily Allowance | Weekly Allowance | Monthly Allowance | Yearly Allowance |
|---|---|---|---|---|---|
| 90.0% | 1 Nine | 2h 24m | 16h 48m | 3d 1h 48m | 36.5 Days |
| 95.0% | 1.5 Nines | 1h 12m | 8h 24m | 1d 12h 54m | 18.26 Days |
| 99.0% | 2 Nines | 14m 24s | 1h 40m | 7h 18m | 3.65 Days |
| 99.5% | 2.5 Nines | 7m 12s | 50m 24s | 3h 39m | 1.83 Days |
| 99.9% | 3 Nines | 1m 26s | 10m 5s | 43m 50s | 8h 46m |
| 99.95% | 3.5 Nines | 43.2s | 5m 2s | 21m 55s | 4h 23m |
| 99.99% | 4 Nines | 8.64s | 1m 0s | 4m 23s | 52m 36s |
| 99.995% | 4.5 Nines | 4.32s | 30.2s | 2m 11s | 26m 18s |
| 99.999% | 5 Nines | 0.86s | 6.05s | 26.3s | 5m 16s |
| 99.9999% | 6 Nines | 0.086s | 0.60s | 2.63s | 31.56s |
Recommended Architecture Stack
Basic Single-Region Deployment
To reliably sustain a 99% SLA without exceeding error budgets, production systems typically implement:
- Single-server Docker host or single-zone VM with basic container restart policies
- Standard automated nightly database backups
- Manual incident recovery and deployment rollbacks
Standard SLA Contract Clause Template
Ready-to-use legal snippet for Master Service Agreements (MSA)
Calculate Custom Outage Durations & Realized Availability
Have you experienced an unexpected API incident? Input your exact downtime duration into our dual-mode calculator to instantly evaluate SLA compliance, credit tier liabilities, and error budget burn.
Frequently Asked Questions (99.0% Uptime)
Clear answers to common SRE, contractual, and technical SLA calculation questions.
Frequently Asked Questions
Generally no for customer-facing production applications, where 7+ hours of monthly downtime will cause high churn. However, 99% is normal and acceptable for internal dashboards, reporting tools, and developer staging environments.
Automate Your SLA Compliance Tracking with Uptara
Eliminate manual downtime spreadsheets. Continuously probe your APIs from global edge regions, aggregate quorum consensus, and export 1-click audit ledgers.