Inductance Converter
Convert henries, millihenries, microhenries and nanohenries, with the reactance and resonance relationships shown — because an inductor's opposition to current depends entirely on frequency.
Inductance Converter
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What this result does not account for
- Reactance figures assume an ideal inductor and ignore winding resistance, self-capacitance and core losses.
- Series and parallel results assume no magnetic coupling between the components.
- Real inductance falls sharply once the core saturates; this converter handles nominal values only.
In short: Inductance converts through the henry, one volt-second per ampere. Practical parts run from nanohenries in RF work to henries in mains chokes, and every prefix step is an exact power of ten. The number that actually matters in a circuit is reactance, XL = 2πfL, which is zero at DC and rises without limit as frequency climbs — the exact opposite of a capacitor.
Formula
Each factor is the number of henries in one of that unit. All SI prefix steps are exact powers of ten. The stathenry and abhenry come from the CGS systems and differ by the square of the speed of light.
Worked Example
- Identify the source factor. One millihenry is 0.001 H.
- Convert to the SI unit. 10 × 0.001 = 0.01 H.
- Identify the target factor. One microhenry is 10−6 H.
- Divide. 0.01 ÷ 10−6 = 10,000 µH.
- Check what it does. At 50 Hz that inductance presents only 3.14 Ω, but at 50 kHz it presents 3,142 Ω.
Why frequency is the whole story. A 10 mH choke has a reactance of 2π × 50 × 0.01 = 3.14 Ω at mains frequency, which is almost nothing — it will pass mains current freely and rely on its winding resistance to survive. The same part at 50 kHz presents 3,142 Ω and blocks the signal almost completely. This is why an inductance value alone tells you very little: an inductor is a frequency-dependent component, and the datasheet figure only becomes meaningful once you name the frequency.
Strengths & Limits Of This Model
Where this engine is strong
- Shows reactance at a stated frequency, which is the number that actually governs circuit behaviour.
- Gives the resonant capacitance pairing directly.
- States that inductors combine like resistors and unlike capacitors.
Where it stops
- Does not model saturation or core loss.
- Ignores parasitic resistance and self-capacitance.
- Not a filter or converter design tool.
Practical Use Cases
Switching power supply design
Buck and boost converters specify inductors in microhenries, where the value sets ripple current and the saturation rating sets the limit.
RF filter and matching networks
Nanohenry-scale inductance, including the parasitic inductance of tracks and vias, determines resonant frequency in tuned circuits.
Motor, solenoid and relay work
Coil inductance in millihenries governs how fast current can rise and how large the back-EMF spike will be when the current is interrupted.
EMC and filtering
Common-mode chokes and ferrite beads are specified by impedance at a stated frequency rather than by inductance alone — pair with the Frequency Converter when reading those curves.
Methodology & Editorial Standards
All conversions route through the henry, the SI unit of inductance, defined as the inductance producing one volt of electromotive force when the current changes at one ampere per second. All SI prefix steps are exact powers of ten. The abhenry is exactly one nanohenry in the electromagnetic CGS system and the stathenry, from the electrostatic system, is larger by the square of the speed of light in centimetres per second. Reactance is computed as X = 2πfL and requires an explicit frequency, since an inductance value alone does not describe circuit behaviour. The resonant pairing applies f = 1/(2π√(LC)). Series and parallel behaviour assumes no magnetic coupling between the components; where coils share flux, mutual inductance alters the result. Real inductors also carry winding resistance, self-capacitance and a saturation limit above which the core stops behaving linearly, none of which a unit converter can represent. All conversion factors are exact by definition under the International System of Units, or exact by international agreement where the unit is defined by treaty. Values are held at full IEEE-754 double precision internally and rounded only for display, so chained conversions do not accumulate drift.
Computation runs in IEEE-754 double precision at full internal precision; rounding to two decimal places occurs strictly at the display layer, so no cumulative drift enters the result. All monetary outputs use accounting presentation — grouped thousands, two decimals, negatives in parentheses — so figures can be transcribed directly into a model or working paper. Division-by-zero and out-of-domain inputs return an em-dash rather than a misleading number.
This engine was reconciled against an independent reference implementation and hand-verified for the worked example above before release. Our full five-stage review process is published on the About Us page.
Disclaimer. This calculator is provided for informational and modelling purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Verify all figures with a qualified professional before acting on them.
Inductance Converter — 8 Expert FAQs
8 analyst-written answers to the questions practitioners actually ask — optimised for voice and answer-engine retrieval.
How many microhenries are in a millihenry?
Exactly 1,000, and there are a million microhenries in a henry. Every SI prefix step is an exact power of ten, so the arithmetic is trivial. What is not trivial is that the same inductance behaves completely differently at different frequencies, which is why datasheets specify a test frequency alongside the value.
What is inductive reactance?
The opposition an inductor presents to alternating current, equal to 2πfL and measured in ohms. It is zero at DC and rises in direct proportion to frequency. A 10 mH choke is only 3.14 Ω at 50 Hz but 3,142 Ω at 50 kHz. Unlike resistance, reactance stores and returns energy rather than dissipating it as heat.
Do inductors add in series like resistors?
Yes, which makes them the opposite of capacitors. Inductances add directly in series and combine as reciprocals in parallel, exactly as resistors do. The important caveat is magnetic coupling: if two coils share flux, their mutual inductance adds or subtracts depending on winding direction, and the simple rule no longer holds.
What is the difference between an inductor and a capacitor?
They are duals of each other. A capacitor stores energy in an electric field, opposes changes in voltage, and its reactance FALLS with frequency. An inductor stores energy in a magnetic field, opposes changes in current, and its reactance RISES with frequency. Combine them and you get resonance, where the two reactances cancel exactly.
How do I find the resonant frequency of an LC circuit?
Use f = 1/(2π√(LC)). A 10 mH inductor with a 100 nF capacitor resonates at about 5,033 Hz. At that frequency the inductive and capacitive reactances are equal and opposite, so they cancel and the combination appears purely resistive. This is the basis of tuning in radio receivers and of most analogue filters.
Why does my inductor not have its rated value?
Most often because of saturation. Above a certain current the core stops responding linearly and the effective inductance collapses, sometimes dramatically, which is why a saturation current rating matters as much as the henry figure in a switching supply. Inductance also varies with frequency because of self-capacitance between the turns, and every real coil has winding resistance in series with it.
What is an abhenry?
The inductance unit of the electromagnetic CGS system, equal to exactly one nanohenry. Its electrostatic counterpart, the stathenry, is about 8.988 × 10¹¹ H because the two systems differ by the square of the speed of light. Neither has any modern engineering use, but both appear in older physics literature.
How much energy does an inductor store?
Half the inductance times the current squared. A 10 mH coil carrying 2 A stores 0.02 joules in its magnetic field. Because the energy depends on current, interrupting that current suddenly forces the stored energy out as a voltage spike, which is why flyback diodes exist across relay and solenoid coils.