⚡ Parallel & Series Resistor Calculator
Calculate equivalent resistance for resistors in parallel or series. Supports 2-10 resistors with current and power calculations.
Configuration
Optional: Provide voltage to calculate branch currents and power dissipation
Resistors (2)
Ready to Calculate
Add resistors and click Calculate to find the equivalent resistance.
Parallel Formula
For two resistors: Req = (R₁ × R₂) / (R₁ + R₂)
In parallel, the equivalent resistance is always less than the smallest resistor. Voltage is the same across all resistors, but current divides.
Series Formula
Simply add all resistor values together.
In series, the equivalent resistance is always greater than the largest resistor. Current is the same through all resistors, but voltage divides.
Understanding Resistor Combinations
Parallel Resistors: Used to reduce overall resistance or to distribute current. Common in LED circuits, voltage dividers, and current-sharing applications.
Series Resistors: Used to increase overall resistance or create voltage dividers. Common in sensor circuits, LED current limiting, and bias networks.
Power Consideration: When resistors share current (parallel) or voltage (series), ensure each resistor's power rating is adequate for its individual dissipation.
Practical Tip: Two equal resistors in parallel have half the resistance. Two equal resistors in series have double the resistance.
Disclaimer
This calculator is provided as-is for educational and informational purposes only. While we strive for accuracy, always verify calculations with professional standards and local electrical codes. Use at your own risk. For critical applications, consult a licensed professional electrician.
Balance Every Network
Model complex resistor networks alongside these partner calculators.
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