Fail fraction and average fail rate FIT

# Fail fraction and average fail rate FIT

The calculators below convert between fail fraction and average fail rate FIT given an operation time.

Fail fraction is probability of failure of a single unit or expected value of proportion of population failed at a given time. FIT is number of failures per 10^9 device-hours.

Say you are given a large number units (n) that have been operating over X hours. Of these n units, a certain number (y) have failed. This calculator extrapolates the Failures in Time (FIT) based on that failure rate. It will tell you how many failures per 10^9 device-hours you can expect given your current set of data.

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### Purpose

Calculates AFR given your failure fraction and the time in operation for the units.

### Equation

\begin{aligned} 10^9 * {(-1)}{\frac{ln(1-FailFraction)}{Hours}} \\ \end{aligned}

FIT - Failures in Time. One FIT equals one failure per billion hours device-hours of operation.

Operation Hours - Represets the number of hours the device is in use.

### Average Fail Rate FIT to Fail Fraction

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### Purpose

Calculates fail fraction given AFR and the operation time in hours.

### Equation

\begin{aligned} 1 - e^{\frac{-FIT * Hours}{10^9}} \\ \end{aligned}

FIT - Failures in Time. One FIT equals one failure per billion hours device-hours of operation.

Operation Hours - Represets the number of hours the device is in use.

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TI provides this data for your convenience. However, there are significant limitations of its usefulness as an indicator of how TI parts (including related software) may perform when used in various applications.

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