Spares Calculator is a scientific tool that allows you to forecast spare parts, optimize inventory and justify investments. Simple graphs and tables make figures easy to interpret and explain to colleagues and customers. Attractive reports enhance proposals, presentations and plans.

Spares Calculator has customers in over 30 countries and is used by OEMs, government agencies, consultancies and universities. Whether you are an engineer, maintenance manager, academic or a professional logistician, Spares Calculator is there to meet your needs.

Mathematical Models

Spares Calculator uses models based on a logarithmic Poisson distribution as prescribed by Dr Sherbrooke and Dr Feeney in their work for the US DoD in the 1960’s. These models are now the industry standard and are used in nearly every spare parts program on the market today.


Spares Calculator was first launch in 2002. Prelaunch the Spares Calculator models were validated in thousands of trials against credible reference texts such as those listed below.

  1. S. Navy, Reliability Engineering Handbook, NAVAIR 01-1A-32
  2. B L Hansen, Quality Control, Prentice Hall Inc. Englewood Cliffs
  3. S. Navy, Maintainability Design Criteria Handbook for Designers of Shipboard Electronic Equipment, NAVSHIPS 94324

Since that time the program has undergone literally hundreds of real-life company trials and is used globally in multiple industries by some of the biggest and most successful companies in the world.

Learn More

To learn more about the theory behind Spares Calculator how we validate our models please visit: