Femtowatt is 1e-15 watt units.
Femtowatts to Ronnawatts Converter — fW to RW
Convert Femtowatt (fW) to Ronnawatt (RW) using the exact conversion factor (1 femtowatt = 1e-42 ronnawatt). See the formula, worked examples, and conversion table.
Femtowatts to Ronnawatts converter
Converter
Engineering Converter
Convert common stress, force, torque, power, and energy units used in engineering.
Context values
Some unit families need one extra value for a physically accurate result.
Ronnawatt is 1e+27 watt units.
Result = input x 1e-15 / 1e+27.
Power units are compatible.
Reserved above the conversion cards and below the converter.
About Converting Femtowatts to Ronnawatts
Femtowatt and Ronnawatt both measure a quantity used in structural or mechanical engineering — commonly stress, pressure, force, torque, power, or energy — where converting between the unit conventions used in different regions, industries, or equipment specifications is a routine part of design work. Specifically: Femtowatt is 1e-15 watt units, and ronnawatt is 1e+27 watt units.
Formula
ronnawatts = femtowatts × 1e-42
This factor comes from each unit's defined relationship to the category's base unit: 1 femtowatt equals 1e-15 base units, and 1 ronnawatt equals 1e+27 base units, so dividing one by the other gives the direct femtowatt-to-ronnawatt factor of 1e-42.
Simple example
1 fW × 1e-42 = 1e-42 RW
1 femtowatt = 1e-42 ronnawatts.
Real-world example
100 fW × 1e-42 = 1e-40 RW
100 femtowatts = 1e-40 ronnawatts.
Conversion table
| Femtowatt (fW) | Ronnawatt (RW) |
|---|---|
| 1 fW | 1e-42 RW |
| 10 fW | 1e-41 RW |
| 50 fW | 5e-41 RW |
| 100 fW | 1e-40 RW |
| 500 fW | 5e-40 RW |
| 1,000 fW | 1e-39 RW |
Reverse conversion: Ronnawatt to Femtowatt
1e-42 RW × 1e+42 = 1 fW
1e-42 ronnawatts = 1 femtowatt.
femtowatts = ronnawatts × 1e+42
For a page dedicated to this direction, see Ronnawatt to Femtowatt.
Understanding the Femtowatt (fW)
Femtowatt is 1e-15 watt units.
Understanding the Ronnawatt (RW)
Ronnawatt is 1e+27 watt units.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many ronnawatts are in 1 femtowatt?
1 femtowatt equals 1e-42 ronnawatts, using the exact defined conversion factor rather than an estimate.
How do I convert femtowatt to ronnawatt?
Multiply the femtowatt value by 1e-42. The converter above does this instantly to whatever precision you set.
How do I convert ronnawatt back to femtowatt?
Use the reverse factor: 1 ronnawatt equals 1e+42 femtowatts. You can also use the swap control in the converter above to flip the direction instantly.
What is a femtowatt?
Femtowatt (fW) is a unit of engineering.
What is a ronnawatt?
Ronnawatt (RW) is a unit of engineering.
Is the femtowatt to ronnawatt conversion exact?
Yes. Both femtowatt and ronnawatt 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.
Why do engineering unit conventions vary so much by region and industry?
Pressure, force, and stress can be expressed in metric (pascal, newton), US customary (psi, pound-force), or older and industry-specific units (atmosphere, torr, kip) depending on the country, industry, and even the equipment manufacturer, which is why engineers routinely need to convert between them when working across specs from different sources.