An uptime SLA is the specific availability guarantee stated in a service level agreement between a provider and customer. It defines the minimum percentage of time the service must be available within a given measurement period (usually monthly). Common uptime SLA tiers include 99% (7.31 hours/month downtime), 99.9% (43.8 minutes/month), 99.95% (21.9 minutes/month), and 99.99% (4.38 minutes/month).
Uptime SLAs typically define what counts as "downtime" (usually inability to serve requests, not just degraded performance), how it's measured (customer-reported vs. provider-monitored), the measurement window (monthly vs. quarterly), and the remedies for breaches (usually service credits — a percentage refund on the monthly bill).
Choosing the right uptime SLA involves balancing customer expectations against engineering cost. Higher availability requires exponentially more investment in redundancy, monitoring, and operational processes. Hyperping's SLA calculator helps teams understand the downtime implications of different SLA percentages and track their actual uptime against their commitments.