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Inductive reactance calculator

Solve the inductive reactance relation XL = 2πfL for any of its three variables. Choose whether to find the reactance, the frequency or the inductance, enter the other two, and it returns the answer — plus, if you supply an RMS voltage, the resulting current and reactive power.

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The Inductive reactance calculator turns Solve for, Frequency f, f unit, Inductance L, L unit, Reactance XL (when solving for f or L), XL unit, RMS voltage (optional) into Inductive reactance XL, Frequency, Inductance, Current (if voltage given), Reactive power (if voltage given), instantly and for free.

How to use it

  1. Enter your values: Solve for, Frequency f, f unit, Inductance L, L unit, Reactance XL (when solving for f or L), XL unit, RMS voltage (optional).
  2. Read the result instantly: Inductive reactance XL, Frequency, Inductance, Current (if voltage given), Reactive power (if voltage given).

Frequently asked questions

What does the Inductive reactance calculator actually compute?

It takes Solve for, Frequency f, f unit, Inductance L, L unit, Reactance XL (when solving for f or L), XL unit and RMS voltage (optional) and derives Inductive reactance XL, Frequency, Inductance, Current (if voltage given) and Reactive power (if voltage given) from them. The calculation is live as you type, so the result updates on every change.

What information do I need to provide?

8 values: Solve for, Frequency f, f unit, Inductance L, L unit, Reactance XL (when solving for f or L), XL unit and RMS voltage (optional) (V). Nothing else is required — no account, no file upload.

Which “Solve for” option should I choose?

You can pick between « Reactance XL », « Frequency f » and « Inductance L ». Each one changes what the calculator works out, so switch and compare — the default is « Reactance XL ».

Which units should I enter the values in?

Enter RMS voltage (optional) V. Metric and US units are both supported — switch system and the figures convert for you.

When would I actually use this?

At the bench: sizing a resistor for an LED, reading a colour band, working out a divider ratio, and checking a part will not cook.

What is the most common mistake?

Choosing a resistance and forgetting the power rating. A value that is electrically right will still burn if the package cannot dissipate what passes through it — check the watts as well as the ohms.

What is the difference between the Inductive reactance calculator and the Impedance calculator (RLC)?

This one returns Frequency and Inductance; the Impedance calculator (RLC) returns Impedance magnitude |Z| and Phase angle. That is the whole difference — open the one whose figure you need.

Is there a tool for the next step?

PCB trace width calculator (IPC-2221) is the closest one after this: Size a printed-circuit-board trace for a given current using the IPC-2221 standard. Enter the current, the allowed temperature rise, the copper weight and whether the trace is external or internal, and it returns the required width in mils and millimetres — plus resistance and voltage drop if you give a length.

What else is worth having open alongside it?

555 timer calculator (astable & monostable) and LED resistor calculator — they come up in the same task often enough to be worth a second tab.

Where do the figures come from, and how current are they?

Ohm's law and the divider formulas are exact. Colour bands follow the IEC standard; real components carry a tolerance, so a nominal value and a measured one will not match exactly.

Further reading

All guides →
How-toHow to Calculate an LED Series ResistorSize the series resistor for any LED with one formula: R = (Vs − Vf) / I. Follow the steps, see a worked 5 V example, and pick the right resistor.ExplainerWhat Is Ohm's Law? V = I × R Explained SimplyOhm's law links voltage, current, and resistance with one equation: V = I × R. Learn the triangle trick and see worked examples.ExplainerThe Voltage Divider: The Formula Is Trivial, the Assumption Behind It Is NotVout = Vin·R2/(R1+R2) is only true when nothing is connected to the output. Draw current and the voltage collapses, by an amount that follows one exact law. Here is that law, the ten-times rule checked against it, and why a lower-resistance divider costs you power forever.ExplainerWhat Is Voltage Drop? Why Long Wires Lose VoltageVoltage drop is the voltage lost along a wire due to its resistance. Learn how length, gauge, and current affect it, and why it matters for your circuits.ExplainerResistors in Series and in Parallel: The Formulas, and the Three Things They Do Not Tell YouSeries adds, parallel adds reciprocals — that part is easy. The parts that catch people: which member dominates the answer, why two 5 % resistors in parallel are still 5 %, and why the smallest resistor in a parallel pair takes the largest share of the power.ComparisonSolar Panels: the Self-Consumption Rate Decides the PaybackSince June 2026 a French rooftop is paid 1.1 cents for an exported kilowatt-hour and avoids 25.61 cents by consuming the same one. That ratio of 23 to 1 makes the self-consumption rate — the variable almost every quote omits — worth more than the amount of sun falling on the roof.