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Mean Time To Failure (Chip) Calculator

Work out mean time to failure (chip) instantly with clear inputs, formula shown and shareable results.

About Mean Time To Failure (Chip) Calculator

FIT is failures per billion device-hours, so MTBF is 1e9 divided by FIT. The Arrhenius factor referenced to a 55 degree use condition shows why junction temperature dominates reliability: at 0.7 eV, running 40 degrees hotter multiplies the failure rate several times over.

Formula

FIT and MTBF

MTBF = 1e9 / FIT; AF = exp((Ea/k)(1/T_ref - 1/T_use))

Worked example

With the default values below, Mean Time To Failure (Chip) Calculator returns MTBF of 310.08. Change any input above and every figure here is recalculated in your browser.

Inputs used

Base failure rate
25 FIT
Junction temperature
95 °C
Activation energy
0.7 eV
Devices in the population
10,000 devices

Results

MTBF
310.08 years
Temperature-adjusted failure rate
368.15 FIT
Failures per year in the population
32.25 failures
Thermal acceleration versus 55 C
14.73 x

Step by step

  1. 1Values used
  2. 2FIT and MTBF
  3. 3MTBF= 310.08 years
  4. 4Temperature-adjusted failure rate= 368.15 FIT
  5. 5Failures per year in the population= 32.25 failures
  6. 6Thermal acceleration versus 55 C= 14.73 x

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Is MTBF the expected life of one part?

No. It is the inverse of the failure rate during the flat part of the bathtub curve. A 100-year MTBF does not mean a part lasts 100 years.

How is fleet failure count derived?

Multiply FIT by device count and hours, then divide by 1e9. That is the figure that matters for warranty and spares planning.

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Mean Time To Failure (Chip) Calculator – Calculate MTBF