Watt is one joule per second.
Watts to Milliwatts Converter — W to mW
Convert Watt (W) to Milliwatt (mW) using the exact conversion factor (1 watt = 1,000 milliwatt). See the formula, worked examples, conversion table, history, and common uses.
Watts to Milliwatts 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.
Milliwatt is 0.001 watt units.
Result = input x 1 / 0.001.
Electrical units in the same family convert directly.
Reserved above the conversion cards and below the converter.
About Converting Watts to Milliwatts
Watt and Milliwatt 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. Watt is most often used for electrical appliance power ratings worldwide.
Formula
milliwatts = watts × 1000
This factor comes from each unit's defined relationship to the category's base unit: 1 watt equals 1 base unit, and 1 milliwatt equals 0.001 base units, so dividing one by the other gives the direct watt-to-milliwatt factor of 1000.
Simple example
1 W × 1000 = 1,000 mW
1 watt = 1,000 milliwatts.
Real-world example
120 W × 1000 = 120,000 mW
120 watts = 120,000 milliwatts.
Conversion table
| Watt (W) | Milliwatt (mW) |
|---|---|
| 1 W | 1,000 mW |
| 5 W | 5,000 mW |
| 12 W | 12,000 mW |
| 24 W | 24,000 mW |
| 120 W | 120,000 mW |
| 240 W | 240,000 mW |
Reverse conversion: Milliwatt to Watt
1 mW × 0.001 = 0.001 W
1 milliwatt = 0.001 watts.
watts = milliwatts × 0.001
For a page dedicated to this direction, see Milliwatt to Watt.
Understanding the Watt
Watt (W) measures power. The watt is the SI derived unit of power: one joule of energy per second. It is classified as a SI derived unit.
Where it's used: Standard scientific and everyday power unit worldwide
Uses of the Watt today
- Electrical appliance power ratings worldwide
- Light bulb brightness-equivalent labeling
- Engine and motor power specifications (alongside horsepower)
History of the Watt
The watt is named after James Watt, whose improvements to the steam engine in the late 18th century were commercially pivotal; ironically, Watt himself used horsepower (a unit he helped popularize) to market his engines. The watt was formally adopted as a unit at the 1889 General Conference on Weights and Measures and became the SI derived unit of power in the 20th century.
Historical origin. Watt was not the invention of a single named person; it developed through the process described above.
Understanding the Milliwatt (mW)
Milliwatt is 0.001 watt units.
Watt — sources
- BIPM SI Brochure — Coherent derived units — Defines the watt as the SI unit of power.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many milliwatts are in 1 watt?
1 watt equals 1,000 milliwatts, using the exact defined conversion factor rather than an estimate.
How do I convert watt to milliwatt?
Multiply the watt value by 1000. The converter above does this instantly to whatever precision you set.
How do I convert milliwatt back to watt?
Use the reverse factor: 1 milliwatt equals 0.001 watts. You can also use the swap control in the converter above to flip the direction instantly.
What is a watt?
Watt (W) measures power. The watt is the SI derived unit of power: one joule of energy per second. It is classified as a SI derived unit.
What is a milliwatt?
Milliwatt (mW) is a unit of electricity.
Is the watt to milliwatt conversion exact?
Yes. Both watt and milliwatt are defined by fixed standards rather than physical artifacts, so the factor of 1000 used above is exact to as many digits as you choose to display.
Where is the watt still used today?
Standard scientific and everyday power unit worldwide
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.