RLC Phase Angle Calculator

About this calculator

In a series RLC circuit driven by an AC source, current lags or leads voltage depending on the balance between inductive and capacitive reactance. The phase angle is φ = arctan((X_L − X_C) / R), where X_L = 2πfL is the inductive reactance, X_C = 1/(2πfC) is the capacitive reactance, and R is the resistance. When X_L exceeds X_C the circuit is inductive and current lags voltage; when X_C dominates the circuit is capacitive and current leads.

This calculator takes R, L, C and frequency to compute that phase angle directly. Electrical engineers use it in AC circuit analysis and when designing power-factor correction, since the phase angle determines how much of the apparent power is actually useful real power, while electronics technicians use it when tuning filter and resonance circuits, where the phase angle passes through zero exactly at resonance.