The difference between MTTA and MTTR explained.

MTTA (Mean Time to Acknowledge) measures how quickly an incident is acknowledged after it's triggered. MTTR (Mean Time to Resolve) measures how long it takes to fully resolve the incident. Both are key incident response metrics used to reduce downtime and improve SLAs.

What is MTTA?

MTTA, or Mean Time to Acknowledge, refers to the average time between when an alert is triggered and when a human acknowledges it. This metric focuses on the responsiveness of on-call engineers or support teams.

A lower MTTA suggests that:

• Alerts are being noticed and triaged quickly.
• Your on-call rotation is working efficiently.
• Escalation policies are properly configured.

What is MTTR?

MTTR, or Mean Time to Resolve, tracks the average duration between the detection of an incident and its full resolution. This includes time spent troubleshooting, fixing the root cause, and verifying the solution.

A lower MTTR means:

• Issues are being diagnosed and resolved efficiently.
• Your tooling and collaboration workflows are effective.
• Customers experience less disruption.

How to Calculate MTTA and MTTR

Both MTTA and MTTR are calculated using simple time-based averages:

• MTTA = (Total time between alert trigger and acknowledgment) / (Number of incidents acknowledged)
• MTTR = (Total time between incident detection and resolution) / (Number of incidents resolved)

To ensure accuracy, incidents should be time-stamped at each phase (triggered, acknowledged, resolved) and tracked consistently via an incident management platform like ilert.

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Example (MTTA):

• Incident 1: Alert triggered at 14:00, acknowledged at 14:02 → 2 minutes
• Incident 2: Alert triggered at 15:00, acknowledged at 15:03 → 3 minutes
• MTTA = (2 + 3) / 2 = 2.5 minutes

Example (MTTR):

• Incident 1: Detected at 09:00, resolved at 09:45 → 45 minutes
• Incident 2: Detected at 11:00, resolved at 12:00 → 60 minutes
• MTTR = (45 + 60) / 2 = 52.5 minutes

Real-World MTTA & MTTR Examples

Below are examples of major outages with recorded MTTA and MTTR values:

• Slack Outage (May 2025): During the database routing incident, the first alert was acknowledged in under 2 minutes (TTA) but took nearly 3 hours (TTR) to fully resolve. 
• Cloudflare Third-Party Storage Failure (June 2025): Cloudflare’s monitoring system triggered an alert for increased error rates, which was acknowledged in 3 minutes (TTA). Due to storage failover complexities, the total resolution time was approximately 45 minutes (TTR). 
• Microsoft 365 Admin Center Outage (April 2025): The incident warning was acknowledged in 4 minutes (TTA), and full service restoration took around 4 hours (TTR).

Why MTTA and MTTR Matter

Both MTTA and MTTR are core SRE and DevOps KPIs. They help organizations:

• Measure and improve incident response performance.
• Detect bottlenecks in alerting and remediation.
• Track SLA compliance across teams and time periods.

Tracking these metrics also surfaces hidden inefficiencies in your incident management process, such as slow acknowledgments, or unclear ownership. By measuring them regularly, engineering leaders gain a clearer picture of both team responsiveness and overall system resilience.

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Discover more in our Incident Management Metrics Guide.

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An analysis of performance clusters in the 2024 State of DevOps report shows that organizations classified as "Elite" achieve both top-tier throughput and stability, indicating that fast recovery times (MTTR) often accompany rapid change lead times. This correlation underscores why monitoring MTTA and MTTR together offers a clearer picture of operational excellence.

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How ilert helps reduce MTTR and MTTA

With ilert, organisations can reduce both MTTA and MTTR with:

• Automated alerting: ilert instantly routes alerts to the right on-call engineers using customizable escalation policies.
• Fast acknowledgement channels: the ilert app, email, phone, and chat tool integrations (Slack, Microsoft Teams) make it easy to acknowledge alerts quickly.
• Context-rich notifications: Alerts include detailed information from monitoring tools, and the ilert Responder helps conduct root cause analysis faster.

Frequently Asked Questions

Q: What’s the difference between MTTA and MTTR?
MTTA measures how quickly, on average, incidents are acknowledged, while MTTR measures how long it takes to fully resolve issues. MTTA focuses on responsiveness while MTTR focuses on resolution efficiency.

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Q: How often should MTTA and MTTR be tracked?
Track these metrics continuously, ideally in real time via an incident management platform, and review them at least monthly to identify trends and areas for improvement.

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Q: Can MTTR include planned maintenance or only unplanned incidents?
MTTR typically measures unplanned incident resolution time. Planned maintenance windows are excluded; separate “maintenance” metrics track planned downtime.

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Q: How do anomalies in MTTA/MTTR data get handled?
Outliers such as major outages or botched upgrades can skew averages. Using median values or percentile-based measures (e.g., 95th percentile MTTR) provide robust insights.

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