Henry is the SI unit of inductance.
Henrys to Rontohenrys Converter — H to rH
Convert Henry (H) to Rontohenry (rH) using the exact conversion factor (1 henry = 1e+27 rontohenry). See the formula, worked examples, conversion table, history, and common uses.
Henrys to Rontohenrys converter
Converter
Electricity Converter
Convert electrical units by family and calculate voltage, current, resistance, power, and energy with context values.
Context values
Some unit families need one extra value for a physically accurate result.
Rontohenry is 1e-27 henry units.
Result = input x 1 / 1e-27.
Electrical units in the same family convert directly.
Reserved above the conversion cards and below the converter.
About Converting Henrys to Rontohenrys
Henry and Rontohenry both belong to the electricity family — voltage, current, resistance, power, or energy — units that show up constantly when working across the different standards used by household wiring (120V/240V depending on region), automotive electrical systems (12V/24V), and electronics design. Henry is most often used for inductor and transformer ratings in electronics.
Formula
rontohenrys = henrys × 1e+27
This factor comes from each unit's defined relationship to the category's base unit: 1 henry equals 1 base unit, and 1 rontohenry equals 1e-27 base units, so dividing one by the other gives the direct henry-to-rontohenry factor of 1e+27.
Simple example
1 H × 1e+27 = 1e+27 rH
1 henry = 1e+27 rontohenrys.
Real-world example
120 H × 1e+27 = 1.2e+29 rH
120 henrys = 1.2e+29 rontohenrys.
Conversion table
| Henry (H) | Rontohenry (rH) |
|---|---|
| 1 H | 1e+27 rH |
| 5 H | 5e+27 rH |
| 12 H | 1.2e+28 rH |
| 24 H | 2.4e+28 rH |
| 120 H | 1.2e+29 rH |
| 240 H | 2.4e+29 rH |
Reverse conversion: Rontohenry to Henry
1e+27 rH × 1e-27 = 1 H
1e+27 rontohenrys = 1 henry.
henrys = rontohenrys × 1e-27
For a page dedicated to this direction, see Rontohenry to Henry.
Understanding the Henry
Henry (H) measures electrical inductance. The SI derived unit of electrical inductance, equal to one volt-second per ampere. It is classified as a SI derived unit.
Where it's used: Universal — SI derived unit used worldwide
Uses of the Henry today
- Inductor and transformer ratings in electronics
- Motor and generator design calculations
- Circuit filtering and signal-processing design
History of the Henry
The henry is named after Joseph Henry (1797–1878), an American scientist who discovered the electromagnetic phenomenon of self-inductance independently of, and at roughly the same time as, Michael Faraday's related discoveries in England.
Historical origin. Henry was not the invention of a single named person; it developed through the process described above.
Understanding the Rontohenry (rH)
Rontohenry is 1e-27 henry units.
Henry — sources
- BIPM SI Brochure, 9th edition — Definition of the henry as a coherent SI derived unit.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many rontohenrys are in 1 henry?
1 henry equals 1e+27 rontohenrys, using the exact defined conversion factor rather than an estimate.
How do I convert henry to rontohenry?
Multiply the henry value by 1e+27. The converter above does this instantly to whatever precision you set.
How do I convert rontohenry back to henry?
Use the reverse factor: 1 rontohenry equals 1e-27 henrys. You can also use the swap control in the converter above to flip the direction instantly.
What is a henry?
Henry (H) measures electrical inductance. The SI derived unit of electrical inductance, equal to one volt-second per ampere. It is classified as a SI derived unit.
What is a rontohenry?
Rontohenry (rH) is a unit of electricity.
Is the henry to rontohenry conversion exact?
Yes. Both henry and rontohenry are defined by fixed standards rather than physical artifacts, so the factor of 1e+27 used above is exact to as many digits as you choose to display.
Where is the henry still used today?
Universal — SI derived unit used worldwide
What's the difference between voltage, current, and resistance?
Voltage (volts) is the electrical potential difference driving current through a circuit. Current (amperes) is the rate of flow of electric charge. Resistance (ohms) is how much a component opposes that flow. They're related by Ohm's law (V = I × R), but they are distinct physical quantities, and this page converts between units of just one of them.