Find Inductance L
Three methods: from X_L and f, from LC resonance, or from V = L dI/dt.
XL Reactance
f Frequency
Results
Inductance
--
Reactance XL
--
Frequency
--
Extra
--
Energy at 1A
--
Method
--
Inductance Calculator
XL method — Measure impedance at a known frequency. L = XL/(2πf). Best for LCR meters.
Resonance method — Find the frequency where an LC circuit resonates. L = 1/(4π²f²C). Best for RF work.
V/dI/dt method — Apply a voltage step and measure dI/dt. L = V·dt/dI. Best for power inductors.
Resonance method — Find the frequency where an LC circuit resonates. L = 1/(4π²f²C). Best for RF work.
V/dI/dt method — Apply a voltage step and measure dI/dt. L = V·dt/dI. Best for power inductors.
Inductance Calculator
Three independent methods to find an unknown inductance from measurable quantities. Use the reactance method with an LCR meter, the resonance method for RF circuits, or the V/dI/dt method for power inductors. Each method works best in different situations.
Method 1: From Reactance XL and Frequency
L = XL / (2πf)
Measure the impedance at a known frequency using an LCR meter.
XL = 50 Ω at 100 kHz → L = 50 / (2π × 100000) = 79.6 µH
Measure the impedance at a known frequency using an LCR meter.
XL = 50 Ω at 100 kHz → L = 50 / (2π × 100000) = 79.6 µH
{body_sibs['rl-time-constant']} {all_sibs['rl-time-constant'][1]}.
Method 2: From LC Resonant Frequency
L = 1 / (4π²f²C)
Connect the unknown inductor with a known capacitor and find the resonant frequency.
f = 1 MHz, C = 100 pF → L = 253 µH
Connect the unknown inductor with a known capacitor and find the resonant frequency.
f = 1 MHz, C = 100 pF → L = 253 µH
Method 3: From V = L dI/dt
L = V × dt / dI
Apply a known voltage and measure the rate of current change.
V = 5V, dI = 100 mA in 10 µs → L = 5 × 10µs / 100mA = 500 µH
Apply a known voltage and measure the rate of current change.
V = 5V, dI = 100 mA in 10 µs → L = 5 × 10µs / 100mA = 500 µH
{body_sibs['inductor-current']} {all_sibs['inductor-current'][1]}. {body_sibs['helical-coil']} {all_sibs['helical-coil'][1]}.
Frequently Asked Questions
How does this fit in the inductor calculator family?
Each inductor calculator covers a different aspect: energy storage, current rise, time constant, mutual coupling, load analysis, physical design (solenoid, helical, toroid), and measurement (inductance calculator). Use them together for complete inductor design.
Last updated: March 2026