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

## 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?

1. 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.

2. Next, determine the total number of failures during the time period.

In this case, the air-conditioning failed a total of 5 times.

3. 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