Milliwatt is 0.001 watt units.
Milliwatts to Yoctowatts Converter — mW to yW
Convert Milliwatt (mW) to Yoctowatt (yW) using the exact conversion factor (1 milliwatt = 1e+21 yoctowatt). See the formula, worked examples, and conversion table.
Milliwatts to Yoctowatts converter
Converter
Power Converter
Convert watts, horsepower, refrigeration tons, BTU per hour, and engineering power units.
Context values
Some unit families need one extra value for a physically accurate result.
Yoctowatt is 1e-24 watt units.
Result = input x 0.001 / 1e-24.
Power uses the watt as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Milliwatts to Yoctowatts
Milliwatt and Yoctowatt both describe power output, and the conversion is a routine part of comparing an engine or motor's spec sheet across countries that use different power units. Specifically: Milliwatt is 0.001 watt units, and yoctowatt is 1e-24 watt units.
Formula
yoctowatts = milliwatts × 1e+21
This factor comes from each unit's defined relationship to the category's base unit: 1 milliwatt equals 0.001 base units, and 1 yoctowatt equals 1e-24 base units, so dividing one by the other gives the direct milliwatt-to-yoctowatt factor of 1e+21.
Simple example
1 mW × 1e+21 = 1e+21 yW
1 milliwatt = 1e+21 yoctowatts.
Real-world example
100 mW × 1e+21 = 1e+23 yW
100 milliwatts = 1e+23 yoctowatts.
Conversion table
| Milliwatt (mW) | Yoctowatt (yW) |
|---|---|
| 1 mW | 1e+21 yW |
| 10 mW | 1e+22 yW |
| 100 mW | 1e+23 yW |
| 500 mW | 5e+23 yW |
| 1,000 mW | 1e+24 yW |
| 5,000 mW | 5e+24 yW |
Reverse conversion: Yoctowatt to Milliwatt
1e+21 yW × 1e-21 = 1 mW
1e+21 yoctowatts = 1 milliwatt.
milliwatts = yoctowatts × 1e-21
For a page dedicated to this direction, see Yoctowatt to Milliwatt.
Understanding the Milliwatt (mW)
Milliwatt is 0.001 watt units.
Understanding the Yoctowatt (yW)
Yoctowatt is 1e-24 watt units.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many yoctowatts are in 1 milliwatt?
1 milliwatt equals 1e+21 yoctowatts, using the exact defined conversion factor rather than an estimate.
How do I convert milliwatt to yoctowatt?
Multiply the milliwatt value by 1e+21. The converter above does this instantly to whatever precision you set.
How do I convert yoctowatt back to milliwatt?
Use the reverse factor: 1 yoctowatt equals 1e-21 milliwatts. You can also use the swap control in the converter above to flip the direction instantly.
What is a milliwatt?
Milliwatt (mW) is a unit of power.
What is a yoctowatt?
Yoctowatt (yW) is a unit of power.
Is the milliwatt to yoctowatt conversion exact?
Yes. Both milliwatt and yoctowatt 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.