Calculating Allowable Downtime by Uptime Percentage
99.9% uptime allows up to 8.77 hours of downtime per year. 99.99% high availability allows only 52.6 minutes per year.
eCommerce & Scale
6 min read
Aug 25, 2026
SLA (Service Level Agreement) Guarantees: 99.9% vs 99.99% Uptime Calculations
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Published by ZodHost Engineering Team
Executive Summary & Key Takeaways
Understand what high-availability uptime SLA numbers mean in actual allowable annual downtime minutes and infrastructure redundancy.
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