An SLA (Service Level Agreement) is the external, contractual commitment between buyer and vendor. An OLA (Operational Level Agreement) is the internal commitment between teams or sub-suppliers that underpins the SLA. A KPI (Key Performance Indicator) is the specific metric used to measure whether the SLA is being met. Most SLA disputes are not about the threshold — they are about which KPI is used to measure it.
SLA — Service Level Agreement.
The contractually committed performance threshold between the buyer and the vendor. SLAs typically cover availability, response time, resolution time, and quality metrics. Breaching the SLA has financial or service-credit consequences spelled out in the contract.
An SLA is only as good as its definitions. "99.9% availability" sounds firm until you ask: availability of what, measured at which point in the architecture, with which exclusions, over what reporting period. Two vendors offering "99.9% availability" can deliver materially different actual uptime depending on those four answers.
OLA — Operational Level Agreement.
The internal commitments — between teams within the vendor's organization, or between the vendor and its sub-suppliers — that underpin the SLA. The OLA is invisible to the buyer in normal circumstances, but it determines whether the SLA can actually be delivered. A vendor that promises a 4-hour response SLA but whose internal incident-management OLA is "best effort" will miss the SLA repeatedly.
For the buyer, the practical implication is that strong SLAs require evidence of strong OLAs underneath. In a structured RFP, this is one of the things the document asks vendors to demonstrate, not just promise.
KPI — Key Performance Indicator.
The specific, measurable metric used to evaluate performance. KPIs operationalize the SLA — they say how the SLA threshold will be measured. The choice of KPI is often where the loophole hides.
Worked example: an SLA committing to "P1 incident resolution within 4 hours" sounds clear. But the underlying KPI may be defined as "elapsed time from incident acknowledgement to status-change to resolved." Acknowledgement can be delayed; status-change can be applied to incidents that aren't actually resolved; reopened incidents can be excluded; certain incident categories can fall outside scope. Each is a small definitional choice; cumulatively they can move the apparent KPI by 30–50%.
Where most SLA disputes actually live.
Across the engagements we run, the most common SLA dispute is not about the threshold being missed. It is about whether the KPI used to measure it accurately reflects what the buyer thought they were buying. The fix is upstream: define the KPI mechanics in the contract, not in a separate operational document that can be reinterpreted later.
The contract checklist.
- Define the SLA threshold with specific numerical targets and reporting period.
- Define the KPI mechanics — how the metric is calculated, what is included, what is excluded, when the clock starts and stops.
- Require OLA evidence — for tier-1 services, request the operational-level agreements that underpin the SLA, in summary form, attached to the contract.
- Set service-credit consequences — financial or operational consequences for missed SLAs that are large enough to drive vendor behaviour.
- Reserve verification rights — the right to independently verify SLA reports against ticket-level or telemetry data.
FAQ.
What is the difference between SLA and OLA?
An SLA is the external, contractual commitment between buyer and vendor. An OLA is the internal commitment between teams or sub-suppliers that supports the SLA. The OLA is invisible to the buyer but essential for SLA delivery.
What is a KPI in the context of SLAs?
A KPI is the specific metric used to measure whether the SLA threshold is being met. The choice of KPI — what it measures, when the clock starts and stops, what is included or excluded — is often where SLA disputes actually originate.
Should KPI definitions be in the contract?
Yes. Defining the SLA threshold without defining the KPI mechanics that measure it leaves room for reinterpretation later. Both should be unambiguous in the executed contract.
