Resistor Derating Calculator
Select a derating standard (NASA Level 1/2/3, MIL-STD-975, or Commercial), enter resistor specs and ambient temperature, and instantly see derated power, voltage limits, and safety margins with a visual temperature derating curve.
Derating Standard
Resistor Specifications
Ambient Temperature
Derating Results
Temperature Derating Curve
What is Resistor Derating?
Resistor derating is the practice of using a resistor below its maximum rated power and voltage to improve reliability. Aerospace (NASA EEE-INST-002) and military (MIL-STD-975) standards define specific derating rules — typically limiting power to 50-80% of rated and applying linear derating above a knee temperature. This is critical for high-reliability applications in space, aviation, and defense.
How to Use the Resistor Derating Calculator
- Select a derating standard (NASA Level 1 for space, MIL-STD-975 for military, or Commercial)
- Enter the resistor's rated power (W), rated voltage (V), and resistance (Ω)
- Adjust the ambient temperature using the slider or input field
- Review the derated power, voltage limit, maximum current, and safety margin
- Use the temperature derating curve chart to visualize the operating point
Frequently Asked Questions
What is the difference between NASA Level 1, 2, and 3?
NASA EEE-INST-002 defines three levels: Level 1 (50% power, most strict) for critical space missions, Level 2 (60% power) for general spacecraft, Level 3 (80% power) for non-critical applications.
What is a knee temperature in derating?
The knee temperature is the point above which linear derating begins. Below this temperature, derated power remains constant. Above it, allowable power decreases linearly until reaching zero at the maximum temperature.
Why is derating important for aerospace electronics?
In space environments, component failure can be catastrophic and repair is impossible. Derating provides safety margins against manufacturing variations, aging, and thermal stress. NASA standards have demonstrated that proper derating significantly reduces failure rates.