Millihenries to Henries Converter

How to Convert Millihenries to Henries

To convert an inductance measurement from millihenries to henries, divide the inductance value by the conversion factor. Since one millihenry is equal to 0.001 henries, you can use this formula:

The inductance in henries is equal to the millihenries divided by 1,000.

How Many Henries Are in a Millihenry?

There are 0.001 henries in one millihenry.

What Is a Millihenry?

The millihenry (symbol: mH) is a unit of electrical inductance equal to one thousandth (10⁻³) of a henry. The prefix “milli” denotes a factor of 10⁻³ in the International System of Units. Millihenries are commonly used for medium-sized inductors in power electronics, audio equipment, and industrial control systems. The inductors in audio crossover networks, which split the audio signal into frequency bands for different speakers, typically have values of 0.1–10 mH. In power electronics, the main energy-storage inductors in DC-DC converters often have values of 0.1–10 mH for lower-frequency designs. Filter inductors used to smooth rectified AC in power supplies typically range from 1–100 mH. Relay coils, solenoid valves, and small electromagnets typically have inductance values of 10–500 mH. The voice coil of a typical loudspeaker has an inductance of 0.5–3 mH, which affects the speaker’s impedance at high frequencies.

One millihenry is equal to:

• 0.001 henries (H)
• 1,000 microhenries (μH)
• 10⁶ abhenries (abH)
• 1.1127 × 10⁻¹⁵ stathenries (stH)

What Is a Henry?

The henry (symbol: H) is the SI derived unit of electrical inductance, named after the American scientist Joseph Henry who independently discovered electromagnetic induction around the same time as Michael Faraday. One henry is defined as the inductance of a circuit in which an electromotive force (EMF) of one volt is produced when the current through the circuit changes at a rate of one ampere per second (1 H = 1 V·s/A = 1 kg·m²/(s²·A²)). In practical terms, one henry is a very large inductance. Most electronic components have inductance values measured in millihenries (μH) or microhenries (mH). However, large power transformers and reactor coils can have inductance values of several henries. Inductance is the property of an electrical conductor that opposes a change in current flowing through it. When current flows through a conductor, it creates a magnetic field around it. If the current changes, the magnetic field changes, which induces a voltage that opposes the change (Lenz’s law). This self-induced voltage is proportional to the rate of change of current, with the proportionality constant being the inductance. The henry is also used to measure mutual inductance between two conductors, where a change in current in one conductor induces a voltage in the other.

One henry is equal to:

• 1,000 millihenries (mH)
• 1,000,000 microhenries (μH)
• 10⁹ abhenries (abH)
• 1.1127 × 10⁻¹² stathenries (stH)
• 0.001 kilohenries (kH)

Understanding Electrical Inductance Units

Inductance is the property of an electrical conductor by which a change in current flowing through it induces an electromotive force (EMF) in the conductor itself (self-inductance) or in a nearby conductor (mutual inductance). It is one of the fundamental quantities in electromagnetism, along with resistance and capacitance.

The physical basis of inductance is Faraday’s law of electromagnetic induction: a changing magnetic field induces an electric field. When current flows through a conductor, it creates a magnetic field. If the current changes, the magnetic field changes, which induces a voltage that opposes the change in current (Lenz’s law). The ratio of the induced voltage to the rate of current change is the inductance.

Major Unit Families

• SI units: The henry (H) is the SI unit of inductance, with standard metric prefixes: μH (microhenry, 10⁻⁶ H), mH (millihenry, 10⁻³ H), kH (kilohenry, 10³ H), MH (megahenry, 10⁶ H), GH (gigahenry, 10⁹ H).
• CGS-EMU: The abhenry (abH) is the inductance unit in the CGS electromagnetic system. 1 abH = 10⁻⁹ H = 1 nanohenry. It is a very small unit.
• CGS-ESU: The stathenry (stH) is the inductance unit in the CGS electrostatic system. 1 stH ≈ 8.988 × 10¹¹ H. It is an enormously large unit due to the factor of c² in the conversion.

Inductance in Practice

• Electronic components: Chip inductors: 0.001–1,000 μH. Power inductors: 0.1–100 mH. Transformers: 0.01–100 H.
• Parasitic inductance: PCB traces: ~1 nH/cm. IC bond wires: 1–5 nH. Through-hole vias: 0.5–2 nH.
• Audio equipment: Speaker voice coils: 0.5–3 mH. Crossover network inductors: 0.1–10 mH.
• Power systems: Large power transformers: 0.1–10 H. Reactor coils: 0.01–1 H.

Converting Between Inductance Units

All inductance units measure the same physical quantity, so converting between them is a matter of multiplying by the appropriate conversion factor. For SI prefix conversions, each step is a factor of 1,000. The CGS conversions involve fixed factors: 1 abH = 10⁻⁹ H (exact) and 1 stH = c² × 10⁻⁹ H (where c ≈ 2.998 × 10¹⁰ cm/s).

Tips for Inductance Conversions

• For SI metric conversions (μH, mH, H, kH, MH, GH), each prefix step is a factor of 1,000.
• The abhenry equals exactly 10⁻⁹ henries, which is the same as 1 nanohenry (nH). This makes conversion straightforward.
• The stathenry is enormous: 1 stH ≈ 899 billion henries. The conversion factor involves the speed of light squared (c²).
• The ratio of 1 stathenry to 1 abhenry is c² (in CGS units) ≈ 8.988 × 10²⁰. This reflects the fundamental relationship between electrostatic and electromagnetic units.
• Most practical electronic inductors have values between 0.01 μH and 100 mH. Very few components exceed 10 H.
• When reading component datasheets, pay attention to whether the inductance is in μH, mH, or H. A factor-of-1,000 error can be catastrophic in circuit design.
• In RF (radio frequency) circuits, inductance values are typically in the 0.1–100 μH range. In power electronics, they are typically 1–100 mH.

Millihenries to Henries Conversion Table

The following table shows conversions from millihenries to henries.

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