Inductive Reactance Calculator

How it is calculated

The tool applies XL = 2 × π × f × L, where f is the frequency in hertz (Hz) and L is the inductance in henries (H). The answer is in ohms (Ω) and is rounded to two decimals. The engine does no unit conversion: it multiplies the numbers exactly as entered, so a value in millihenries or kilohertz must be converted to henries and hertz first or the result will be off by a factor of 1,000.

Both inputs must be greater than zero; zero, negative or empty values give no result. Reactance rises in direct proportion to frequency and to inductance, so doubling either one doubles X_L. It describes an ideal inductor and ignores the winding resistance of a real coil.

Common mistakes

• Entering millihenries or microhenries as if they were henries. 100 mH must be typed as 0.1, otherwise the answer is 1,000 times too large.
• Entering kHz or MHz without converting to Hz. A 1 MHz signal is 1000000, not 1.
• Using angular frequency ω (rad/s) as f. The 2π is already in the formula, so entering ω counts it twice.
• Treating reactance as resistance. X_L is in ohms but the current lags the voltage by 90°, so it cannot simply be added to a resistor value; the two combine as vectors.
• Expecting a result at 0 Hz (DC). The tool needs a frequency above zero, and an ideal inductor has zero reactance at DC anyway.