Quick answer
Inductive reactance X_L = 2π f L. A 10 mH inductor at 60 Hz has a reactance of 3.7699 Ω.
Enter the inductance and frequency. The calculator returns reactance and the inductance in henries.
Related tools: Voltage Divider Calculator: Output voltage of a two-resistor divider. RLC Impedance Calculator: Impedance and phase angle of a series RLC circuit. RMS Voltage Calculator: Convert between RMS, peak and peak-to-peak voltage of a sine wave.
How to use the Inductive Reactance Calculator
- Enter inductance (mH) (above 0).
- Enter frequency (Hz) (above 0).
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Inductance | A number, in mH | > 0 |
| Frequency | A number, in Hz | > 0 |
Formula and method
Formula
X_L = 2πfL
IEEE-754 double precision; shown to the decimals indicated.
Ideal inductor.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Inductance = 10; Frequency = 60.
| Result | Value |
|---|---|
| Inductive reactance | 3.7699 Ω |
| Inductance in henries | 0.01 H |
Example 2
Inputs: Inductance = 0.5; Frequency = 100000.
| Result | Value |
|---|---|
| Inductive reactance | 314.1593 Ω |
| Inductance in henries | 0.0005 H |
Example 3
Inputs: Inductance = 100; Frequency = 50.
| Result | Value |
|---|---|
| Inductive reactance | 31.4159 Ω |
| Inductance in henries | 0.1 H |
The first line is the headline result (inductive reactance). Below it the inductive Reactance Calculator lists inductance in henries, which describe the same case from other angles. IEEE-754 double precision; shown to the decimals indicated.
Frequency dependence
Reactance rises in proportion to frequency: at 600 Hz the same coil has 37.7 Ω. At DC (0 Hz) an ideal inductor is a short circuit, and at high frequency it blocks current, which is why inductors filter noise.
Real inductors
Real inductors also have winding resistance and parasitic capacitance, so they behave differently at very high frequencies. Reactance is measured in ohms but is not dissipated as heat in an ideal coil.
How the result changes with inductance
Holding every other input at the first worked example, this table changes only inductance. It shows how sensitive the answer is to that one value; each row was produced by running this calculator.
| Inductance | Inductive reactance | Inductance in henries |
|---|---|---|
| 5 | 1.885 Ω | 0.005 H |
| 10 | 3.7699 Ω | 0.01 H |
| 20 | 7.5398 Ω | 0.02 H |
| 40 | 15.0796 Ω | 0.04 H |
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Inductance: entering "0" shows "Inductance must be greater than 0." beside that field and no result.
- Frequency: entering "0" shows "Frequency must be greater than 0." beside that field and no result.
Choosing between the Inductive Reactance Calculator and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Voltage Divider Calculator](/engineering/voltage-divider-calculator/) | input voltage, r1 and r2 | Output voltage |
| [RLC Impedance Calculator](/engineering/rlc-impedance-calculator/) | resistance, inductance and capacitance | Impedance |
| [RMS Voltage Calculator](/engineering/rms-voltage-calculator/) | i know the and voltage | RMS voltage |
| [Parallel Plate Capacitor Calculator](/engineering/parallel-plate-capacitance-calculator/) | plate area, plate separation and relative permittivity εr | Capacitance |
| [Current Divider Calculator](/engineering/current-divider-calculator/) | total current, r1 and r2 | Current through R1 |
Background: electrical circuits
Ohm's law links voltage, current and resistance: V = I × R, so I = V ÷ R and R = V ÷ I. Power is P = V × I, which also equals I² × R and V² ÷ R.
These relations hold for ohmic components, where resistance is constant. Diodes and transistors are non-linear, and in AC circuits with reactive parts impedance (Z) takes the place of resistance. Check component ratings and local electrical code before relying on any calculation.
Assumptions and limitations
- Real inductors also have winding resistance
Use results as engineering estimates and check them against the governing standards, safety factors and a qualified engineer's judgement before relying on them.
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for inductance and frequency to confirm this.
Frequently asked questions
What is the unit of inductance?
The henry (H). Practical coils are quoted in millihenries or microhenries.
Does reactance depend on current?
No, in a linear inductor.
What is the opposite for capacitors?
Capacitive reactance falls as frequency rises.
What does the Inductive Reactance Calculator calculate?
Reactance of an inductor at a frequency. It returns Inductive reactance and Inductance in henries.
What formula does the Inductive Reactance Calculator use?
X_L = 2πfL. Ideal inductor.
What do I need to enter in the inductive Reactance Calculator?
You enter Inductance (mH) and Frequency (Hz).
How is the result rounded or limited?
IEEE-754 double precision; shown to the decimals indicated. Real inductors also have winding resistance.
What is an example of a inductive Reactance result?
With inductance 10 and frequency 60, the inductive reactance is 3.7699 Ω.
Can I rely on this calculator for a decision?
Use results as engineering estimates and check them against the governing standards, safety factors and a qualified engineer's judgement before relying on them. For this calculator in particular: Real inductors also have winding resistance.
Related calculators
- Voltage Divider Calculator — Output voltage of a two-resistor divider.
- RLC Impedance Calculator — Impedance and phase angle of a series RLC circuit.
- RMS Voltage Calculator — Convert between RMS, peak and peak-to-peak voltage of a sine wave.
- Parallel Plate Capacitor Calculator — Capacitance of two parallel plates.
- Current Divider Calculator — Current through each of two parallel resistors.
- RC Circuit Calculator — Time constant, cutoff frequency and charge level of an RC circuit.
- Series Resistance Calculator — Total resistance of resistors in series.
- Capacitance Calculator — Capacitance from charge and voltage.
- Inductance Calculator — Inductance of a long air- or core-filled solenoid.
Sources
- OpenStax, University Physics Volume 2 (Rice University): electricity, circuits and thermodynamics
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.