About
Reliability calculations without the spreadsheet.
ReliabilityCalc is a free set of calculators and quality tools for maintenance, reliability, and quality engineers. It covers the everyday numbers — MTBF, MTTR, availability, OEE — through to Weibull analysis, FMEA, process capability, and Gage R&R.
- Calculators
- 19
- Quality tools
- 7
- Converters
- 3
- Price
- Free
- Account needed
- No
How the numbers are worked out
Each calculator uses the standard textbook definition of its metric — for example availability as MTBF / (MTBF + MTTR), and OEE as availability × performance × quality.
Every equation is published on the formulas page with its symbols and units, and the worked examples walk through real inputs step by step, so you can check a result by hand or cite the method in a report.
What happens to your data
Calculations run entirely in your browser. The numbers you type into a calculator or quality tool are not sent to our servers.
Like most free sites, ReliabilityCalc is supported by advertising and measures traffic: it uses Google Analytics, Google AdSense, and a simple first-party page-view counter. The privacy policy explains exactly what is collected.
Who it’s for
Maintenance engineers tracking equipment KPIs, quality engineers preparing IATF 16949 or ISO 9001 documentation, operations managers who need a number for a review, and students learning how these metrics are used in practice.
Who maintains it
ReliabilityCalc is built and maintained by Ajesh BS, a mechanical engineer working in industrial maintenance and a certified Lean Six Sigma Black Belt. The methods here are the ones used day to day on the shop floor.
Found a mistake?
If a result looks wrong or a formula needs a better reference, please get in touch.