Failure in Time Calculator
What is a FIT Calculator?
FIT (Failures‑in‑Time) is a reliability metric that expresses the number of expected failures per 109 device‑hours. The calculator converts raw test data or an MTBF figure into FIT, and vice‑versa, so reliability engineers can compare components, justify burn‑in hours, and meet customer specifications.
If you need a deeper reliability analysis, you can also estimate equipment lifespan more precisely using a mean time between failures calculation tool.
How to use
- Pick a Calculation Type:
- Failures & Total Hours – you know the number of failures and the combined operating hours.
- Units Tested & Hours Each – you ran N units for t hours each and counted failures.
- MTBF → FIT – you already have an MTBF value and need the equivalent FIT.
- Fill in the highlighted fields for your chosen mode.
Tip: the hour selectors let you enter raw hours, ×1 000 hours, or ×1 000 000 hours for long tests. - Click Calculate FIT. The blue box shows both results:
- FIT – failures per 109 device‑hours
- MTBF – mean time between failures (hours)
- Switch modes at any time; the previous output hides automatically. Use Reset to clear every input.
Benefits
- One‑click conversions – no manual 109 scaling or spreadsheet math.
- Three entry modes cover most lab and field‑test data formats.
- Unit helpers for kilohours and megahours streamline large‑sample calculations.
Disclaimer: This calculator provides estimated FIT and MTBF values to support reliability planning and analysis. Actual reliability performance can vary based on operating conditions, environment, and component quality. For critical applications, it is recommended to confirm results using manufacturer data or detailed engineering evaluation.