Enter the total number of failures and the total amount of time into the calculator to determine the failure rate.

Failure Rate, MTBF, FIT & AFR Calculator

Use the main converter to switch between failure rate, MTBF, FIT, AFR, and expected failures. Use the second tab to calculate reliability at a specific time.
Converter
Reliability at Time t
Failures + Operating Time
MTBF
FIT
Annual Failure Rate (AFR)
Enter a known value set and calculate the matching failure metrics.

Results

Failure Rate
MTBF
MTBF in Days
MTBF in Years
FIT
Annual Failure Rate
Expected Failures
Average Time Between Failures
Failure Rate
MTBF
FIT
AFR
This tab calculates reliability using the exponential reliability model R(t) = e-λt.

Results

Reliability R(t)
Failure Probability 1 – R(t)
Reliability %
Expected Failures Over Mission Time

Failure Rate Formula

The following formula is used to calculate a failure rate. 

fr = TF / TT
  • Where fr is the failure rate (failures/time)
  • TF is the total amount of failures
  • TT is the total amount of time

To calculate a failure rate, divide the total mount of failures by the total amount of time.

Failure Rate Definition

What is a failure rate? A failure rate is a measure of the total number of failures that occur in a given amount of time. Most often this metric is used in industries such as manufacturing to describe failures in equipment or produced goods.

Example Problem

How to calculate failure rate?

  1. First, determine the total number of failures.

    For this example, there were found to be 20 equipment failures through an entire manufacturing plant.

  2. Next, determine the total time.

    The total time that elapsed during the time period was 40 hours.

  3. Finally, calculate the failure rate.

    Using the formula above the failure rate is found to be .5 failures per hour.

About Failure Rate

What is an acceptable failure rate? An acceptable failure rate is entirely dependent on the application, personal or company goals, and many other factors. For example, in certain industries, such as medical fields, failure rates of less than .01% are expected.