Zeptowatt is 1e-21 watt units.
Zeptowatts to Milliwatts Converter — zW to mW
Convert Zeptowatt (zW) to Milliwatt (mW) using the exact conversion factor (1 zeptowatt = 1e-18 milliwatt). See the formula, worked examples, and conversion table.
Zeptowatts to Milliwatts 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.
Milliwatt is 0.001 watt units.
Result = input x 1e-21 / 0.001.
Power uses the watt as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Zeptowatts to Milliwatts
Zeptowatt and Milliwatt 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: Zeptowatt is 1e-21 watt units, and milliwatt is 0.001 watt units.
Formula
milliwatts = zeptowatts × 1e-18
This factor comes from each unit's defined relationship to the category's base unit: 1 zeptowatt equals 1e-21 base units, and 1 milliwatt equals 0.001 base units, so dividing one by the other gives the direct zeptowatt-to-milliwatt factor of 1e-18.
Simple example
1 zW × 1e-18 = 1e-18 mW
1 zeptowatt = 1e-18 milliwatts.
Real-world example
100 zW × 1e-18 = 1e-16 mW
100 zeptowatts = 1e-16 milliwatts.
Conversion table
| Zeptowatt (zW) | Milliwatt (mW) |
|---|---|
| 1 zW | 1e-18 mW |
| 10 zW | 1e-17 mW |
| 100 zW | 1e-16 mW |
| 500 zW | 5e-16 mW |
| 1,000 zW | 1e-15 mW |
| 5,000 zW | 5e-15 mW |
Reverse conversion: Milliwatt to Zeptowatt
1e-18 mW × 1e+18 = 1 zW
1e-18 milliwatts = 1 zeptowatts.
zeptowatts = milliwatts × 1e+18
For a page dedicated to this direction, see Milliwatt to Zeptowatt.
Understanding the Zeptowatt (zW)
Zeptowatt is 1e-21 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 zeptowatt?
1 zeptowatt equals 1e-18 milliwatts, using the exact defined conversion factor rather than an estimate.
How do I convert zeptowatt to milliwatt?
Multiply the zeptowatt value by 1e-18. The converter above does this instantly to whatever precision you set.
How do I convert milliwatt back to zeptowatt?
Use the reverse factor: 1 milliwatt equals 1e+18 zeptowatts. You can also use the swap control in the converter above to flip the direction instantly.
What is a zeptowatt?
Zeptowatt (zW) is a unit of power.
What is a milliwatt?
Milliwatt (mW) is a unit of power.
Is the zeptowatt to milliwatt conversion exact?
Yes. Both zeptowatt and milliwatt are defined by fixed standards rather than physical artifacts, so the factor of 1e-18 used above is exact to as many digits as you choose to display.