What does MTTR stand for?
MTTR stands for Mean Time to Repair. The average time needed to repair a failed component and restore service. A lower MTTR means faster recovery.
MTTR is the average time needed to bring a failed system back into service. It measures how quickly you recover, so lower is better. You calculate it by dividing total repair time by the number of repairs. It is a measured result from past incidents, which makes it different from RTO, a target set in advance.
MTTR in practice: an example
A payment service had three outages this quarter lasting 30, 90 and 60 minutes. MTTR is 180 minutes divided by 3, so 60 minutes. The business set an RTO of 45 minutes for this service, so the team is recovering more slowly than the target and needs better runbooks or automation.
What MTTR is confused with
MTTR vs MTBF: what is the difference?
MTTR is about how long repairs take; MTBF is about how often failures happen. What MTBF stands for
MTTR vs RTO: what is the difference?
RTO is the maximum recovery time the business accepts, decided beforehand. MTTR is what recovery actually took, on average. What RTO stands for
Which exams cover MTTR?
MTTR is on the official CompTIA acronym list for two of the four exams covered here.
- Security+ SY0-801: 3.4 (Security Architecture).
- Network+ N10-009: 3.0 (Network Operations).
Each number is a CompTIA exam objective and the name in brackets is its domain. The exam puts the term in a scenario; it does not ask you to recite the expansion.
Check yourself: two practice questions
Written by CertSprint for this page. They are not taken from any exam.
1. A system failed four times and the repairs took 2, 4, 3 and 3 hours. What is the MTTR?
- 3 hours
- 4 hours
- 12 hours
- 48 hours
Show the answer
A. 3 hours. Total repair time is 12 hours over 4 repairs, so MTTR is 3 hours.
2. Which change is most likely to lower MTTR?
- Buying more reliable hardware
- Keeping tested recovery runbooks and spare parts on site
- Extending the backup retention period
- Reducing the number of users
Show the answer
B. Keeping tested recovery runbooks and spare parts on site. MTTR depends on how fast you repair. More reliable hardware raises MTBF instead, because it reduces how often failures happen.
Sources: NIST glossary: mean time to recovery; NIST SP 800-34 Rev. 1, Contingency Planning Guide. The acronym and its expansion come from CompTIA's official acronym lists, linked from each exam glossary above. The explanation, example and questions are CertSprint's own, checked against these sources on 11 November 2026.