Convert Henries to Femtohenries
Henry (H) to Femtohenry (fH) inductance conversion — enter any value below to get an instant result, or use the table for common values.
Results from this calculator are estimates provided for general informational purposes only, based on formulas, rates, and standards commonly accepted as of 2026. Figures may differ slightly from other calculators or professional sources due to rounding methods, differing assumptions, or regional regulations, and rules may change over time. Always consult a qualified professional — such as a financial advisor, healthcare provider, or other relevant specialist — before making decisions based on these results.
Result
1 H = 1E+15 fH
1 Henry = 1E+15 Femtohenries
1 Femtohenry = 1E-15 Henries
1 H in every supported unit
Conversion chart: Henry to Femtohenries
Conversion table
| Henry (H) | Femtohenry (fH) |
|---|---|
| 0.01 H | 1E+13 fH |
| 0.1 H | 1E+14 fH |
| 1 H | 1E+15 fH |
| 2 H | 2E+15 fH |
| 3 H | 3E+15 fH |
| 5 H | 5E+15 fH |
| 10 H | 1E+16 fH |
| 20 H | 2E+16 fH |
| 50 H | 5E+16 fH |
| 100 H | 1E+17 fH |
| 1000 H | 1E+18 fH |
Henry (H)
Definition: The SI derived unit of electrical inductance — the property of a circuit element that opposes a change in current. One henry is defined as the inductance of a circuit in which one volt of electromotive force is produced when the current changes at a rate of one ampere per second.
History: Named in 1893 by the International Electrical Congress in honor of American scientist Joseph Henry, who independently discovered electromagnetic self-induction in the early 1830s around the same time as Michael Faraday's induction work, though Faraday published first.
Current use: The standard unit for rating inductors, transformer windings, and motor coils; most everyday components are far smaller than a full henry, so practical values are almost always expressed in millihenries or microhenries instead.
Femtohenry (fH)
Definition: One quadrillionth of a henry (1 fH = 10⁻¹⁵ H), an extremely small inductance unit at the edge of what is practically measurable.
History: It emerged from the same SI prefix ladder used for femtofarad-scale capacitance, applied where advanced semiconductor and superconducting circuit research needed to quantify inductance below the picohenry scale.
Current use: Found mainly in advanced research contexts such as superconducting quantum circuit design and precision on-chip interconnect modeling, where inductance at this scale meaningfully influences circuit behavior.
Supported Units
| Unit | Symbol | In Henry |
|---|---|---|
| Henry | H | 1 H |
| Kilohenry | kH | 1000 H |
| Millihenry | mH | 0.001 H |
| Microhenry | µH | 1E-06 H |
| Nanohenry | nH | 1E-09 H |
| Picohenry | pH | 1E-12 H |
| Femtohenry | fH | 1E-15 H |
| Abhenry | abH | 1E-09 H |
| Stathenry | statH | 8.98755E+11 H |
| Weber/Ampere | Wb/A | 1 H |
About These Parameters
- Value
- The inductance value you want to convert, expressed in the "From" unit. Accepts decimals, and can represent anything from a tiny nanohenry PCB-trace parasitic to a large power-transformer winding's multi-henry rating.
- From Unit
- The unit your input value is currently measured in — an inductor datasheet's millihenry or microhenry rating, or a historical figure quoted in abhenries or stathenries from the older CGS unit systems.
- To Unit
- The unit you want the result converted into. Use the swap button to flip From and To instantly, handy when translating a datasheet value into a different SI-prefixed scale or back to the base henry.
How Inductance Conversion Works
The Formula
Every unit here is defined by a fixed multiplier relative to the henry. To convert a value from one unit to another:
result = value × (factor of "From" unit ÷ factor of "To" unit)
For Henry → Femtohenry: multiply by 1E+15. For example, 1 H × 1E+15 = 1E+15 fH.
Why Inductors Span Such a Wide Range of Units
A henry is a relatively large amount of inductance for a physical coil to produce — winding enough turns around a large enough core to reach a full henry generally means a bulky component, the kind found in mains-frequency power transformers and large chokes. Most inductors used in switching power supplies, RF circuits, and signal filtering only need a fraction of a henry to do their job, which is why millihenries and microhenries are the everyday scale for real components. At the other extreme, any wire, PCB trace, or connector lead has some small amount of unavoidable "parasitic" inductance — usually measured in nanohenries or picohenries — that becomes significant only at the high frequencies and fast switching speeds used in modern digital and RF electronics.
SI Henries vs. CGS Abhenries and Stathenries
Before the SI system unified electrical units around the henry, volt, and ampere, 19th-century physicists worked in the centimeter-gram-second (CGS) system, which split into two competing branches: the electromagnetic (emu) branch, whose inductance unit is the abhenry (equal to a tiny one billionth of a henry), and the electrostatic (esu) branch, whose unit is the stathenry (equal to a massive 898.8 billion henries). That enormous gap — the mirror image of the abfarad/statfarad relationship in capacitance — comes from the same speed-of-light-squared relationship that links the esu and emu systems throughout classical electromagnetism. Modern electronics almost never uses either CGS unit directly, but they still turn up when translating older theoretical physics texts into today's henry-based units.
Example
An inductance of 1 H equals 1E+15 fH. For scale, a small RF inductor on a circuit board might be rated around 10 microhenries, a typical switching power-supply inductor might be a few hundred microhenries to a few millihenries, and a large mains-frequency power transformer winding can reach several henries.
Frequently Asked Questions
How many Femtohenries are in 1 Henry?
1 Henry (H) equals exactly 1E+15 Femtohenries (fH).
Why are inductors almost never rated in whole henries?
A henry is a relatively large amount of inductance to build into a small, practical coil — reaching a full henry typically requires a bulky winding around a large magnetic core, the kind used in mains-frequency transformers. Everyday inductors in power supplies, RF circuits, and filters only need a fraction of a henry, so they're rated in millihenries or microhenries instead.
Is weber/ampere the same thing as a henry?
Yes — they're mathematically identical. The henry is defined as exactly one weber of magnetic flux linkage per ampere of current (1 H = 1 Wb/A), so expressing an inductance in webers per ampere gives the exact same numeric value as expressing it in henries.
Why is the stathenry so much larger than the abhenry?
Both come from the older centimeter-gram-second (CGS) system, but from opposite branches: the abhenry is a CGS electromagnetic (emu) unit, while the stathenry is a CGS electrostatic (esu) unit. The two branches are related by the speed of light squared, which is why the abhenry (10⁻⁹ henries) and stathenry (about 8.9876 × 10¹¹ henries) sit roughly 21 orders of magnitude apart despite both measuring inductance.
What's a typical inductance value for common electronics?
It depends heavily on the application: RF and high-frequency tuning circuits often use nanohenry to microhenry inductors, switching power-supply inductors commonly range from a few microhenries to a few millihenries, and large mains-frequency transformer or motor windings can reach several henries. Kilohenry-scale inductance is essentially never seen outside specialized grid equipment.