What is Reliability?

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What is Reliability?

Reliability is the ability of a system or component to perform its intended function under specified conditions for an extended period without failure. A reliable product has a high probability of performing as expected over time. The reliability of a product can be measured by how long it will last before failing and how often it fails.

In other words, a reliable product does not fail. It performs consistently and predictably.

The following are some examples of products that have been designed with reliability in mind:

  • A car engine that starts every time you turn the key.
  • An airplane that flies safely through turbulence.
  • A medical device that works properly when used on patients.
  • A refrigerator that keeps food fresh.
  • A telephone switchboard that connects calls correctly.
  • A nuclear power plant that operates safely.

Measuring Reliability

The measure of a product's reliability can often be quantified in terms of mean time between failures (MTBF) for repairable products, or mean time to failure (MTTF) for non-repairable products. These metrics offer a statistical basis for understanding how long a product is likely to function before experiencing a failure, allowing manufacturers to set and meet reliability targets.

Improving Reliability

Reliability can be improved by designing products and systems to reduce the likelihood of failure, using high-quality materials, and conducting thorough testing and maintenance. Achieving high reliability requires a multi-faceted approach, including:

  • Design Excellence: Incorporating reliability into the design process ensures that products are built to withstand their operating environment and usage conditions.
  • Quality Materials: Using high-quality components reduces the likelihood of premature failure.
  • Rigorous Testing: Simulating a wide range of operating conditions and stressors can identify potential failures before they occur in real-world use.
  • Preventive Maintenance: Regular maintenance can extend the life of products and systems, especially in industrial applications.
  • Root Cause Analysis: Understanding why failures occur is key to preventing them in future designs.


In conclusion, reliability is a critical component of product quality that affects customer satisfaction, brand reputation, and operational efficiency. By prioritizing reliability in design, materials selection, manufacturing, and maintenance, companies can create products that stand the test of time. As one of Garvin's eight dimensions of product quality, reliability not only signifies the durability and consistency of a product but also reflects a commitment to excellence from its creators.


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