Femtoohm is 1e-15 ohm units.
Femtoohms to Ronnaohms Converter — fOhm to ROhm
Convert Femtoohm (fOhm) to Ronnaohm (ROhm) using the exact conversion factor (1 femtoohm = 1e-42 ronnaohm). See the formula, worked examples, and conversion table.
Femtoohms to Ronnaohms 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.
Ronnaohm is 1e+27 ohm units.
Result = input x 1e-15 / 1e+27.
Electrical units in the same family convert directly.
Reserved above the conversion cards and below the converter.
About Converting Femtoohms to Ronnaohms
Femtoohm and Ronnaohm 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. Specifically: Femtoohm is 1e-15 ohm units, and ronnaohm is 1e+27 ohm units.
Formula
ronnaohms = femtoohms × 1e-42
This factor comes from each unit's defined relationship to the category's base unit: 1 femtoohm equals 1e-15 base units, and 1 ronnaohm equals 1e+27 base units, so dividing one by the other gives the direct femtoohm-to-ronnaohm factor of 1e-42.
Simple example
1 fOhm × 1e-42 = 1e-42 ROhm
1 femtoohm = 1e-42 ronnaohms.
Real-world example
120 fOhm × 1e-42 = 1.2e-40 ROhm
120 femtoohms = 1.2e-40 ronnaohms.
Conversion table
| Femtoohm (fOhm) | Ronnaohm (ROhm) |
|---|---|
| 1 fOhm | 1e-42 ROhm |
| 5 fOhm | 5e-42 ROhm |
| 12 fOhm | 1.2e-41 ROhm |
| 24 fOhm | 2.4e-41 ROhm |
| 120 fOhm | 1.2e-40 ROhm |
| 240 fOhm | 2.4e-40 ROhm |
Reverse conversion: Ronnaohm to Femtoohm
1e-42 ROhm × 1e+42 = 1 fOhm
1e-42 ronnaohms = 1 femtoohm.
femtoohms = ronnaohms × 1e+42
For a page dedicated to this direction, see Ronnaohm to Femtoohm.
Understanding the Femtoohm (fOhm)
Femtoohm is 1e-15 ohm units.
Understanding the Ronnaohm (ROhm)
Ronnaohm is 1e+27 ohm units.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many ronnaohms are in 1 femtoohm?
1 femtoohm equals 1e-42 ronnaohms, using the exact defined conversion factor rather than an estimate.
How do I convert femtoohm to ronnaohm?
Multiply the femtoohm value by 1e-42. The converter above does this instantly to whatever precision you set.
How do I convert ronnaohm back to femtoohm?
Use the reverse factor: 1 ronnaohm equals 1e+42 femtoohms. You can also use the swap control in the converter above to flip the direction instantly.
What is a femtoohm?
Femtoohm (fOhm) is a unit of electricity.
What is a ronnaohm?
Ronnaohm (ROhm) is a unit of electricity.
Is the femtoohm to ronnaohm conversion exact?
Yes. Both femtoohm and ronnaohm are defined by fixed standards rather than physical artifacts, so the factor of 1e-42 used above is exact to as many digits as you choose to display.
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.