Inductive reactance, XL, is how strongly an inductor opposes alternating current, in ohms: XL = 2π × f × L. It rises with frequency and inductance, so the same 100 mH inductor gives about 37.7 Ω at 60 Hz and 31.4 Ω at 50 Hz.
The same inductor behaves differently on a 50 Hz and a 60 Hz supply. Pick your country to load the local frequency and voltage, then read the reactance and the current it lets through.
Result
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Formula
- XL = 2π × f × L
- I = V ÷ XL
How to use it
- Pick your country to load frequency and voltage.
- Enter the inductance in mH.
- Read XL and current. Leave voltage empty for XL only.
This is an estimating tool. Follow your local electrical code and have a qualified electrician confirm any real installation.
Frequently asked questions
What is inductive reactance?
When current through an inductor changes, the inductor builds a voltage that pushes back against the change. AC changes all the time, so an inductor opposes it much like a resistance. Once DC settles it stops changing and the reactance falls to almost zero.
How is reactance different from resistance?
Resistance turns energy into heat. Reactance stores energy in a magnetic field and hands it back every cycle, so it uses no real power, and it makes the current lag the voltage by 90 degrees.
Why do 50 Hz and 60 Hz give different answers?
Reactance is proportional to frequency, so at 60 Hz it is 1.2 times the 50 Hz value. A coil or motor moved between countries with different supply frequencies draws a different current.
