Enter the total operational time and the total number of failures into the calculator to determine the mean time between failures (MTBF).

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## MTBF Formula

The following formula is used to calculate the mean time between failures.

MTBF = TOT / TF

- Where MTBF is the mean time between failures
- TOT is the total operational time (hours)
- TF is the total number of failures

To calculate the mean time between failures, divide the total operational time by the total failures.

## MTBF Definition

**What is MTBF?**

MTBF, short for mean time between failures, is a metric that describes the average time it takes to incur a failure on a piece of equipment.

The equipment can be manufacturing equipment that produces goods or something like air-conditioning.

## Example Problem

How to calculate MTBF?

**First, determine the total hours of operation.**For this example, we are looking at an air-conditioning unit that has been running for a year straight. This is equal to 8760 hours of operation.

**Next, determine the total number of failures during the time period.**In this case, the air-conditioning failed a total of 5 times.

**Finally, calculate the MTBF.**Using the formula above the mean time between failures is calculated to be:

MTBF = TOT / TF

MTBF = 8760/5

MTBF = 1752 hours/failure