Inductance Calculator
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What is a Inductance Calculator Converter?
An inductance converter is a tool that converts between units of electrical inductance such as henrys, millihenrys, microhenrys, and nanohenrys. It is essential for electronics design, transformer calculations, and filter circuit analysis where inductors of various sizes are used.
History of Inductance Calculator Measurement
The henry is named after Joseph Henry, who independently discovered electromagnetic induction in the 1830s alongside Michael Faraday. Henry was the first to wind insulated wire around iron cores to create powerful electromagnets. The abhenry (1 nH) is a CGS electromagnetic unit from older literature.
About This Inductance Calculator Converter
This inductance converter supports 17 units including henry, millihenry, microhenry, nanohenry, attohenry, kilohenry, megahenry, gigahenry, terahenry, petahenry, exahenry, hectohenry, abhenry, stathenry, weber/ampere, and EMU/ESU of inductance.
Understanding Electrical Inductance
Inductance is the property of an electrical conductor that opposes changes in current flowing through it. When current through an inductor changes, it induces a voltage proportional to the rate of change (V = L × dI/dt). The SI unit is the henry (H), defined as the inductance that produces one volt when the current changes at one ampere per second. Named after Joseph Henry, the henry is used across power electronics, RF engineering, and electromagnetic design.
Inductance conversion between metric prefixes (H, mH, µH, nH) is essential in power supply design (filter inductors in mH), RF circuits (matching networks in nH), sensor design (proximity sensors in µH), and motor control (stator inductance in mH). A switch-mode power supply designer might need a 47 µH inductor, while an RF engineer works with 2.2 nH for impedance matching at GHz frequencies. Converting between these prefixes ensures proper component selection and performance calculations.
How to Convert Between Inductance Units
Inductance conversion uses standard SI metric prefixes:
- The prefix chain: H → mH → µH → nH → pH, each step ×1000.
- From henry to millihenry: 1 H = 1000 mH.
- From millihenry to microhenry: 1 mH = 1000 µH.
- From microhenry to nanohenry: 1 µH = 1000 nH.
- Verify: 1 H = 10³ mH = 10⁶ µH = 10⁹ nH = 10¹² pH.
Key Inductance Conversion Formulas
Standard metric prefix conversions for inductance:
- 1 H (henry) = 1000 mH (millihenry)
- 1 mH = 1000 µH (microhenry)
- 1 µH = 1000 nH (nanohenry)
- 1 nH = 1000 pH (picohenry)
- 1 H = 10⁶ µH = 10⁹ nH
- 1 H = 1 V·s/A = 1 Wb/A (definition)
- 1 abhenry (CGS) = 10⁻⁹ H = 1 nH
Worked Examples — Inductance Conversions
Example 1: A buck converter requires a 33 µH inductor. Express in millihenry and nanohenry.
Solution:
To mH: 33 µH ÷ 1000 = 0.033 mH.
To nH: 33 µH × 1000 = 33,000 nH.
Answer: 33 µH = 0.033 mH = 33,000 nH — a typical value for switch-mode power supplies.
Example 2: An RF matching network uses a 4.7 nH inductor. What is this in µH?
Solution:
Conversion: 1 µH = 1000 nH.
Divide: 4.7 ÷ 1000 = 0.0047 µH.
Answer: 4.7 nH = 0.0047 µH — typical for multi-GHz RF impedance matching.
Example 3: A motor stator has inductance of 15 mH. Express in henry and microhenry.
Solution:
To H: 15 ÷ 1000 = 0.015 H.
To µH: 15 × 1000 = 15,000 µH.
Answer: 15 mH = 0.015 H = 15,000 µH — typical for small motor phase inductance.
Example 4: A PCB via has parasitic inductance of 0.5 nH. Calculate voltage spike for dI/dt = 2 A/ns.
Solution:
V = L × dI/dt.
L = 0.5 nH = 0.5 × 10⁻⁹ H.
dI/dt = 2 A/ns = 2 × 10⁹ A/s.
V = 0.5 × 10⁻⁹ × 2 × 10⁹ = 1.0 V.
Answer: 0.5 nH with 2 A/ns switching produces a 1V spike — significant in high-speed digital circuits.
Inductance Conversion Quick Reference
Common inductance conversions for power and RF electronics:
| From | To |
|---|---|
| 1 H | 1000 mH |
| 1 mH | 1000 µH |
| 1 µH | 1000 nH |
| 1 nH | 1000 pH |
| 1 H | 10⁶ µH |
| 1 H | 10⁹ nH |
| 1 mH | 10⁶ nH |
| 1 µH | 0.001 mH |
| 1 nH | 0.001 µH |
| 1 abhenry | 1 nH |
| 100 µH | 0.1 mH |
| 10 nH | 0.01 µH |
Understanding Inductance Measurement Systems
The henry is an SI derived unit: 1 H = 1 V·s/A = 1 Wb/A = 1 kg·m²/(A²·s²). It is named after Joseph Henry, who independently discovered electromagnetic induction around the same time as Faraday. The henry relates magnetic flux linkage to current: L = NΦ/I. For practical inductors, the henry is large — a 1 H inductor would be physically enormous. Most electronics use mH (power), µH (switching converters), and nH (RF/microwave).
The CGS system used the abhenry (= 10⁻⁹ H = 1 nH) as its inductance unit, now completely obsolete. The stathenry (CGS-ESU, ≈ 8.99 × 10¹¹ H) is also defunct. In modern engineering, only the henry with SI prefixes is used. Component manufacturers specify inductors in µH and nH universally. The inductance of a wire or trace (parasitic inductance) is approximately 1 nH per mm of length for typical geometries — this "rule of thumb" helps engineers estimate parasitic effects without detailed calculation.
Real-World Applications of Inductance Conversion
Switch-Mode Power Supplies
Output filter inductors in buck/boost converters are typically 1-1000 µH. The ripple current formula ΔI = V×D/(f×L) requires L in henries. Converting from µH (component label) to H (formula) is essential: 47 µH = 47 × 10⁻⁶ H.
RF & Wireless Design
Impedance matching at GHz frequencies uses nH-scale inductors. A 50Ω match at 2.4 GHz might need 3.3 nH. Converting between nH and µH when switching between design tools and component databases prevents selection errors.
Motor Control
Motor phase inductance (typically 0.5-50 mH) determines current ripple at PWM switching frequency. Drive parameters use mH in user interfaces but calculations need H: 10 mH = 0.01 H for di/dt = V/L computations.
EMC & Signal Integrity
PCB traces, vias, and connectors have parasitic inductance in nH. A 10-nH via at 100 MHz has impedance ωL = 2π × 10⁸ × 10⁻⁸ = 6.3 Ω — significant for signal integrity at high frequencies.
Wireless Power Transfer
Qi charging coils have inductance in µH range. Resonant coupling requires precise inductance values: L = 1/(ω²C) for resonance. Converting between µH and mH ensures correct capacitor pairing for target frequency.
Common Pitfalls in Inductance Conversion
The most dangerous error is confusing mH and µH — a 1000× mistake. Using 47 mH where 47 µH was intended makes a power supply inductor 1000× too large (physically impossible to fit) and using 47 nH where 47 µH was needed makes it 1000× too small (no filtering effect). In calculations, the most common error is forgetting to convert to henries: the formula f = 1/(2π√(LC)) requires L in H and C in F. If L is 100 µH and C is 1 nF: f = 1/(2π√(100×10⁻⁶ × 10⁻⁹)) = 503 kHz. Using 100 and 1 without prefixes would give f = 0.16 Hz — obviously wrong. Also, inductor current rating is separate from inductance value: a 100 µH inductor rated for 500 mA will magnetically saturate if forced to carry 5 A, effectively losing its inductance. This is NOT a unit conversion issue but a common design mistake.
Key Takeaways
- Inductance conversion is pure metric prefix scaling: H → mH → µH → nH → pH, each ×1000.
- 1 H = 1 V·s/A: inductance relates voltage to current change rate (V = L dI/dt).
- Typical ranges: mH (motors, power filters), µH (switching converters), nH (RF/high-speed).
- Parasitic inductance ≈ 1 nH/mm of conductor — fundamental rule of thumb for PCB design.
- Resonant frequency: f = 1/(2π√(LC)). L must be in henries and C in farads for f in hertz.
- The CGS abhenry (= 1 nH) is obsolete — use SI henry with prefixes exclusively.
Metric Conversion Factor Tables for Inductance Converter
| Units to convert | Multiply By The Number | Convert as Unit |
|---|---|---|
| Henry (H) | 1e-9 | Gigahenry (GH) |
| Gigahenry (GH) | 1000000000 | Henry (H) |
| Henry (H) | 0.001 | Kilohenry (kH) |
| Kilohenry (kH) | 1000 | Henry (H) |
| Henry (H) | 1000 | Millihenry (mH) |
| Millihenry (mH) | 0.001 | Henry (H) |
| Henry (H) | 1000000000 | Nanohenry (nH) |
| Nanohenry (nH) | 1e-9 | Henry (H) |
| Henry (H) | 1000000000 | Abhenry (abH) |
| Abhenry (abH) | 1e-9 | Henry (H) |
| Henry (H) | 1000000000000000000 | Attohenry (aH) |
| Attohenry (aH) | 1e-18 | Henry (H) |
| Henry (H) | 1 | Weber/ampere (Wb/A) |
Inductanceconverters & it's abbreviations
| Unit | Abbreviation | Unit | Abbreviation | Unit | Abbreviation |
|---|---|---|---|---|---|
| henry | H | exahenry | EH | petahenry | PH |
| terahenry | TH | gigahenry | GH | megahenry | MH |
| kilohenry | kH | hectohenry | hH | millihenry | mH |
| microhenry | µH | nanohenry | nH | weber/ampere | Wb/A |
| abhenry | abH | EMU of inductance | - | ESU of inductance | - |
Frequently Asked Questions
How do I convert millihenry to microhenry?
Multiply the millihenry value by 1000 to get microhenrys. For example, 2.2 mH × 1000 = 2200 µH.
How do I convert henry to millihenry?
Multiply the henry value by 1000 to get millihenrys. For example, 0.047 H × 1000 = 47 mH.
What is inductance used for?
Inductance is used in transformers, motors, filters, and energy storage. Inductors oppose changes in current, making them essential for power supplies, radio tuning circuits, and electromagnetic interference filtering.
What is the relationship between henry and weber/ampere?
They are identical. 1 henry equals exactly 1 weber per ampere. The henry is simply the special name for this derived SI unit of inductance.
What inductance values are common in electronics?
RF circuits use nanohenrys (1-100 nH). Power supply filters use microhenrys (1-1000 µH). Audio crossovers and power transformers use millihenrys to henrys.
Complete list of Inductance conversion units and its conversion.
- 1 henry = 1.E-9 gigahenry
henry to gigahenry → - 1 gigahenry = 1000000000 henry
gigahenry to henry → - 1 henry = 0.001 kilohenry
henry to kilohenry →
- 1 henry = 1000000000 nanohenry
henry to nanohenry → - 1 nanohenry = 1.E-9 henry
nanohenry to henry → - 1 gigahenry = 1000000 kilohenry
gigahenry to kilohenry →
- 1 henry = 1000000000000000000 attohenry
henry to attohenry → - 1 attohenry = 1.E-18 henry
attohenry to henry → - 1 henry = 1000000000 abhenry
henry to abhenry →
- 1 henry = 1.112650029E-12 stathenry
henry to stathenry → - 1 stathenry = 898755200000 henry
stathenry to henry →
- 1 kilohenry = 1000 henry
kilohenry to henry → - 1 henry = 1000 millihenry
henry to millihenry → - 1 millihenry = 0.001 henry
millihenry to henry →
- 1 gigahenry = 1000 megahenry
gigahenry to megahenry → - 1 megahenry = 0.001 gigahenry
megahenry to gigahenry → - 1 megahenry = 1000 kilohenry
megahenry to kilohenry →
- 1 abhenry = 1.E-9 henry
abhenry to henry → - 1 EMU of inductance = 1.112650029E-21 ESU of inductance
EMU of inductane to ESU of inductane → - 1 ESU of inductance = 898755200000007100000 EMU of inductance
ESU of inductane to EMU of inductane →