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Probability of Failure Formula:
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Probability of Failure (PF) is a fundamental concept in reliability engineering and risk assessment that quantifies the likelihood that a system, component, or process will fail to perform its intended function. It is calculated as the complement of reliability.
The calculator uses the Probability of Failure formula:
Where:
Explanation: This formula represents the fundamental relationship between reliability and failure probability. Since reliability and failure probability must sum to 1, the probability of failure is simply 1 minus the reliability.
Details: Calculating probability of failure is crucial for risk assessment, safety analysis, quality control, and decision-making in engineering, manufacturing, and project management. It helps identify potential weaknesses and prioritize improvement efforts.
Tips: Enter reliability as a decimal value between 0 and 1. For example, 95% reliability should be entered as 0.95. The calculator will automatically compute the corresponding probability of failure.
Q1: What is the difference between reliability and probability of failure?
A: Reliability represents the probability of success, while probability of failure represents the probability of failure. They are complementary probabilities that sum to 1.
Q2: How do I convert percentage reliability to decimal?
A: Divide the percentage by 100. For example, 85% reliability becomes 0.85, and 99.9% reliability becomes 0.999.
Q3: What is considered a good reliability value?
A: This depends on the application. For critical systems (medical, aerospace), reliability above 0.999 is often required. For less critical applications, 0.95-0.99 may be acceptable.
Q4: Can probability of failure be greater than 1?
A: No, probability values must be between 0 and 1 inclusive. A probability of failure of 1 means certain failure, while 0 means no chance of failure.
Q5: How is this used in real-world applications?
A: PF calculations are used in failure mode effects analysis (FMEA), reliability-centered maintenance, safety systems design, and quality assurance across industries.