Inductance converter

The henry (H) is the base unit of inductance, and like capacitance, most real-world components sit well below a full henry: a millihenry (mH) is 0.001 H, a microhenry (µH) is 1e-6 H, a nanohenry (nH) is 1e-9 H, and a picohenry (pH) is 1e-12 H, while a kilohenry (kH), 1,000 H, shows up mainly in large power-grid chokes and specialized lab inductors. The CGS-derived abhenry is tiny, equal to 1e-9 H (the same size as a nanohenry, by coincidence of how that older system was built), while the stathenry is enormous at 898,755,178,736.8176 H. The weber per ampere (Wb/A) is inductance's defining ratio, flux linkage over current, written as a unit name, and it equals exactly 1 H.

The featured pair converts microhenry to millihenry with mH = µH × 0.001, and the reverse multiplies by 1,000.

A 330 µH power-supply inductor converts to 330 × 0.001 = 0.33 mH. A small 15 nH PCB trace inductance steps up to 0.015 µH when you need the microhenry scale, and a 2.2 mH audio-crossover inductor converts down to 2,200 µH if a parts catalog lists it that way instead.

Inductance's practical range mirrors capacitance's but for magnetic rather than electric energy storage. Nanohenry values describe the unavoidable inductance of PCB traces, connector pins, and IC bond wires, which matters a great deal in high-speed digital and RF design because even a few nanohenries can distort a fast signal edge. Microhenry and millihenry inductors are the backbone of switching power supplies, where they store energy each switching cycle, and henry-scale chokes and transformer windings appear in grid-frequency power equipment and audio crossover networks.

A frequent mix-up is forgetting that microhenry and millihenry differ by a factor of 1,000, not 100, the same trap that catches people converting ohms and resistors — it's easy to misplace a zero when scanning a datasheet quickly. It's also worth noting that the abhenry and nanohenry happen to share the same numeric value (1e-9) purely by how the historical CGS electromagnetic system was constructed, which is a coincidence rather than any deeper equivalence between the two unit systems.

It's also easy to forget that an inductor's measured value depends on the current flowing through it, especially for cores made of iron or ferrite rather than air. As current rises toward a core's saturation point, its effective permeability drops and the inductance quoted on the datasheet (usually measured at a small test current) can fall noticeably at the higher currents the part actually sees in operation — a detail that matters more than any unit-conversion rounding error when a power-supply inductor is being sized for a real load.

Inductors also behave differently at different frequencies in ways a single henry figure can't capture on its own: winding capacitance and core losses both grow with frequency, so a choke that looks like a clean inductance at 60 Hz may present a very different impedance at a switching frequency of 100 kHz or more. Datasheets for high-frequency parts often specify the frequency range over which the quoted inductance value is actually valid, for exactly this reason.