An SLA, or Service Level Agreement, is a contract between a service provider and a customer that defines the expected performance standards — most commonly uptime percentage. For example, a 99.99% SLA guarantees no more than 52.6 minutes of downtime per year.
SLAs typically specify the uptime target, how uptime is measured, what counts as downtime, the reporting period, and the remedies or credits available when the provider fails to meet the target. Breaking an SLA can result in service credits, contract termination, or reputational damage.
SLAs should not be confused with SLOs (internal targets) or SLIs (the actual measurements). An SLA is the external commitment to customers, while SLOs and SLIs are the internal mechanisms used to ensure the SLA is met. Hyperping's SLA calculator helps teams understand the downtime budget implied by any SLA percentage.
SLI, SLO and SLA
The three terms describe the same reliability target at increasing levels of commitment. An SLI (Service Level Indicator) is the raw measurement: the actual number your monitoring reports, such as the percentage of requests served successfully or the share of checks that passed in the last 30 days. An SLO (Service Level Objective) is the internal target you hold that indicator to, for example 99.9% of checks passing. An SLA (Service Level Agreement) is the external, contractual version of that objective, with financial consequences attached when you miss it.
In practice the SLI is what you measure, the SLO is what you aim for, and the SLA is what you promise a customer in writing. Teams usually set the SLO tighter than the SLA so there is room to react before a contractual breach. Uptime monitoring supplies the SLI: without a measurement taken from outside your infrastructure, the objective and the agreement are both unverifiable.
