Question 1

What is a service level agreement (SLA)?

Accepted Answer

A service level agreement is a contract — or a section within a larger contract — that defines measurable performance standards a service provider must meet when delivering services to a client. Unlike a general service agreement that describes what services will be provided, an SLA specifies how well those services must be performed, using quantified metrics such as uptime percentage, response time, resolution time, throughput, error rate, and availability windows. The SLA also defines the consequences when the provider fails to meet these standards — typically service credits (partial refunds), escalation procedures, the right to terminate, or liquidated damages. SLAs originated in the IT outsourcing industry but are now standard in cloud computing (SaaS, IaaS, PaaS), managed services, telecommunications, facilities management, logistics, and any service engagement where performance can be objectively measured.

Question 2

What is the difference between an SLA, an SLO, and an SLI?

Accepted Answer

These three terms form a hierarchy of service performance management. A Service Level Indicator (SLI) is the actual measured metric — for example, the percentage of HTTP requests that return a successful response in under 200 milliseconds. A Service Level Objective (SLO) is the target value or range for an SLI — for example, '99.9% of requests will respond successfully in under 200ms over a rolling 30-day period.' An SLO is an internal performance goal. A Service Level Agreement (SLA) is the contractual commitment built on top of SLOs — it states the SLO, defines how it will be measured, and specifies the financial consequences (credits, penalties, termination rights) if the SLO is not met. In practice, organizations set internal SLOs that are slightly more aggressive than their external SLA commitments, creating a buffer that allows them to detect and address degradation before it triggers contractual penalties.

Question 3

What does 'five nines' (99.999%) uptime mean in practice?

Accepted Answer

Uptime percentages translate to specific amounts of allowable downtime per year. 99% uptime allows 3.65 days of downtime per year — generally unacceptable for critical services. 99.9% ('three nines') allows 8.77 hours per year. 99.95% allows 4.38 hours per year. 99.99% ('four nines') allows 52.60 minutes per year. 99.999% ('five nines') allows only 5.26 minutes per year — this is the standard for mission-critical financial systems, emergency services infrastructure, and core telecommunications. Each additional nine represents a tenfold reduction in allowable downtime and typically requires a significant increase in infrastructure investment (redundant systems, geographic failover, automated recovery). When negotiating an SLA, both parties should understand exactly how much downtime each uptime tier permits and whether that tolerance aligns with the client's business requirements.

Question 4

How are SLA credits calculated?

Accepted Answer

SLA credits are the most common remedy for service failures and are typically calculated as a percentage of the monthly service fee corresponding to the severity of the breach. A common structure provides: 10% credit for uptime between 99.0% and 99.9% (a minor breach); 25% credit for uptime between 95.0% and 99.0% (a significant breach); and 50% credit for uptime below 95.0% (a major breach). Most SLAs cap total credits at 100% of the monthly fee for the affected service — meaning the maximum remedy is a full month's refund, not additional damages. Credits are usually applied to future invoices rather than paid in cash. Some SLAs provide that credits are the client's sole and exclusive remedy for SLA failures, which means the client cannot sue for consequential damages caused by the downtime. Clients should negotiate to ensure the credit structure provides meaningful compensation relative to the business impact of service failures.

Question 5

What should an SLA exclude from downtime calculations?

Accepted Answer

Most SLAs define 'Excluded Downtime' — periods that do not count against the uptime metric. Common exclusions include: scheduled maintenance windows (typically communicated at least 48-72 hours in advance, performed during off-peak hours); force majeure events (natural disasters, widespread internet outages, government actions); downtime caused by the client's systems, code, or configuration; third-party service failures outside the provider's control (such as an upstream DNS provider outage); and time during which the client blocks the provider from performing remediation. The SLA should define each exclusion precisely — vague exclusions give the provider too much latitude to avoid accountability. Clients should negotiate for narrow exclusions and should require that scheduled maintenance be performed during defined windows and not exceed a maximum number of hours per month.

Question 6

How should response time and resolution time be defined?

Accepted Answer

Response time is the maximum interval between when the client reports an issue (or the provider's monitoring system detects it) and when the provider acknowledges the issue and begins diagnostic work. Resolution time is the maximum interval between issue detection and full restoration of service to the agreed performance level. Both metrics should be defined for each severity level: critical (complete service outage) might require a 15-minute response and 4-hour resolution; high (major feature degradation) might allow a 1-hour response and 8-hour resolution; medium (minor functionality impairment) might allow a 4-hour response and 24-hour resolution; and low (cosmetic issues, feature requests) might allow a 24-hour response and best-effort resolution. The SLA should specify business hours vs. 24/7 coverage and how after-hours incidents are escalated.

Question 7

Can an SLA be a standalone document or must it be part of a larger contract?

Accepted Answer

An SLA can be either. In enterprise IT outsourcing and managed services, the SLA is typically an exhibit or schedule attached to a master services agreement (MSA) that covers the broader commercial terms (pricing, payment, intellectual property, liability, termination). This structure allows the parties to update SLA metrics without renegotiating the entire contract. In SaaS and cloud computing, the SLA is often a standalone document published on the provider's website and incorporated into the terms of service by reference — customers accept it when they subscribe to the service. In both cases, the SLA should be drafted so that it can be read and enforced independently: it should define all key terms, specify the measurement methodology, and include its own remedies section. If the SLA is part of a larger agreement, it should specify how conflicts between the SLA and the MSA are resolved.

Question 8

What is the difference between a customer-based and service-based SLA?

Accepted Answer

A customer-based SLA is negotiated individually with a specific customer and covers all services that customer receives — it may include different metrics for different services and reflects the customer's specific business requirements and bargaining power. This is common in enterprise outsourcing where large customers negotiate bespoke terms. A service-based SLA applies uniformly to all customers of a particular service — every customer gets the same uptime guarantee, the same response time targets, and the same credit structure. This is the standard model for SaaS platforms, cloud infrastructure providers, and telecommunications companies. A third type, a multi-level SLA, combines both: a corporate-level SLA sets baseline terms, a customer-level SLA adds customer-specific commitments, and a service-level SLA addresses individual services. The right structure depends on the provider's business model and the customer's negotiating position.

Question 9

How should an SLA handle disaster recovery and business continuity?

Accepted Answer

A comprehensive SLA should define two critical disaster recovery metrics: Recovery Time Objective (RTO) — the maximum acceptable time between a disaster event and full service restoration; and Recovery Point Objective (RPO) — the maximum acceptable amount of data loss measured in time (for example, an RPO of 1 hour means the provider must be able to restore data to within 1 hour of the failure event). The SLA should specify the provider's disaster recovery infrastructure (geographic redundancy, backup frequency, failover mechanisms), the testing schedule (DR tests should be conducted at least annually), and the provider's notification obligations during a disaster event. For critical services, the SLA should require the provider to maintain a documented business continuity plan and provide the client with evidence of DR testing results.

Question 10

What reporting and monitoring obligations should an SLA include?

Accepted Answer

The SLA should require the provider to deliver regular performance reports — typically monthly — that document actual performance against each SLA metric. Reports should include: measured uptime for each service component, incident logs with timestamps for detection, response, and resolution, root cause analyses for any SLA breaches, trend data showing performance over time, and planned maintenance schedules for the upcoming period. The SLA should specify whether the client has access to real-time monitoring dashboards and whether the provider's monitoring data is the sole basis for SLA calculations or whether the client can submit independent measurements. In disputes, the methodology for measurement often becomes the central issue — the SLA should define the measurement methodology with enough precision to prevent disagreements about whether a breach occurred.

Component	What to Include
Service Description	Specific services covered, components, and boundaries of the SLA
Uptime Guarantee	Monthly or annual uptime percentage, measurement methodology
Severity Levels	Incident classification (Critical, High, Medium, Low) with definitions
Response Times	Maximum acknowledgment time per severity level
Resolution Times	Maximum restoration time per severity level
Escalation Procedures	Contacts, escalation triggers, management notification thresholds
Service Credits	Credit percentages, calculation method, maximum monthly credit cap
Exclusions	Scheduled maintenance, force majeure, client-caused issues
Monitoring & Reporting	Monitoring tools, dashboard access, report frequency and content
DR/BC Requirements	RTO, RPO, failover procedures, DR testing schedule
Review & Amendment	Periodic SLA review schedule, amendment process
Termination Triggers	Chronic SLA breach as grounds for contract termination

Metric	Typical Target	Common In
Uptime %	99.9% - 99.99%	SaaS, cloud hosting, telecom
Response Time	15 min - 4 hrs (by severity)	Managed services, help desk
Resolution Time	4 hrs - 48 hrs (by severity)	IT support, facilities
Latency	< 100ms (p95 or p99)	CDN, API services, trading
Error Rate	< 0.1% of requests	API platforms, payment processing
RTO / RPO	RTO: 4 hrs; RPO: 1 hr	Disaster recovery, backup services
Throughput	Varies by service	Data processing, logistics

Free Service Level Agreement (SLA) Forms

What Is a Service Level Agreement?

Measurable Standards

Financial Accountability

Escalation Framework

SLA Form Preview

Service Level Agreement

Section 1: Service Description

Section 2: Performance Metrics

Section 3: Service Credits

Key Components

How to Create a Service Level Agreement

Define the services and scope

Establish performance metrics

Set severity levels and response targets

Define the measurement methodology

Structure service credits and remedies

Address exclusions and maintenance

Include reporting, review, and termination provisions

Common SLA Metrics

Sample Service Level Agreement

Frequently Asked Questions

Official Resources

Ready to Define Your Service Levels?