What does MTTF mean?

The MTTF (Mean Time to Failure) indicates the average time an object is in operation before it fails. Mean Time to Failure is often used to predict reliability and service life. MTTF is particularly used for replaceable products that either cannot be repaired or where replacement is more cost effective than repair. The higher the MTTF, the fewer failures there are on average.

How is the MTTF calculated?

The MTTF is calculated by dividing the sum of the operating times by the number of objects. The total operating time until the failure of the object is measured.

MTTF = number of operating hours / number of objects.


10 batteries had a total operating time of 20 years.

20/10 = 2 or 2 years

The MTTF or average operating time of a battery was therefore 2 years.

What is the difference between MTTF and MTBF?

MTTF (Mean Time to Failure) and MTBF (Mean Time between Failure) are very similar. The main difference between the two metrics is the type of product being considered. While the MTTF is used for non-repairable or replaceable products, the MTBF refers to repairable objects.

How to use the MTTF?

The MTTF can be used as a decision-making basis for the purchase of replaceable products or parts. If, for example, the MTTF of a product is 3 years, this information can be used to forecast when a new purchase makes sense.

You will find further explanations of terms in our glossary