Yoctowatt is 1e-24 watt units.
Yoctowatts to Milliwatts Converter — yW to mW
Convert Yoctowatt (yW) to Milliwatt (mW) using the exact conversion factor (1 yoctowatt = 1e-21 milliwatt). See the formula, worked examples, and conversion table.
Yoctowatts to Milliwatts 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.
Milliwatt is 0.001 watt units.
Result = input x 1e-24 / 0.001.
Power units are compatible.
Reserved above the conversion cards and below the converter.
About Converting Yoctowatts to Milliwatts
Yoctowatt and Milliwatt 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: Yoctowatt is 1e-24 watt units, and milliwatt is 0.001 watt units.
Formula
milliwatts = yoctowatts × 1e-21
This factor comes from each unit's defined relationship to the category's base unit: 1 yoctowatt equals 1e-24 base units, and 1 milliwatt equals 0.001 base units, so dividing one by the other gives the direct yoctowatt-to-milliwatt factor of 1e-21.
Simple example
1 yW × 1e-21 = 1e-21 mW
1 yoctowatt = 1e-21 milliwatts.
Real-world example
100 yW × 1e-21 = 1e-19 mW
100 yoctowatts = 1e-19 milliwatts.
Conversion table
| Yoctowatt (yW) | Milliwatt (mW) |
|---|---|
| 1 yW | 1e-21 mW |
| 10 yW | 1e-20 mW |
| 50 yW | 5e-20 mW |
| 100 yW | 1e-19 mW |
| 500 yW | 5e-19 mW |
| 1,000 yW | 1e-18 mW |
Reverse conversion: Milliwatt to Yoctowatt
1e-21 mW × 1e+21 = 1 yW
1e-21 milliwatts = 1 yoctowatt.
yoctowatts = milliwatts × 1e+21
For a page dedicated to this direction, see Milliwatt to Yoctowatt.
Understanding the Yoctowatt (yW)
Yoctowatt is 1e-24 watt units.
Understanding the Milliwatt (mW)
Milliwatt is 0.001 watt units.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many milliwatts are in 1 yoctowatt?
1 yoctowatt equals 1e-21 milliwatts, using the exact defined conversion factor rather than an estimate.
How do I convert yoctowatt to milliwatt?
Multiply the yoctowatt value by 1e-21. The converter above does this instantly to whatever precision you set.
How do I convert milliwatt back to yoctowatt?
Use the reverse factor: 1 milliwatt equals 1e+21 yoctowatts. You can also use the swap control in the converter above to flip the direction instantly.
What is a yoctowatt?
Yoctowatt (yW) is a unit of engineering.
What is a milliwatt?
Milliwatt (mW) is a unit of engineering.
Is the yoctowatt to milliwatt conversion exact?
Yes. Both yoctowatt and milliwatt are defined by fixed standards rather than physical artifacts, so the factor of 1e-21 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.