Convert Watts to Milliwatts
1 watt is 1,000 mW. One watt is exactly 1000 milliwatts.
One watt is 1000 milliwatts. To convert watts to milliwatts, multiply by 1000; to go the other way, divide by 1000 or multiply by 0.001. The factor is exact rather than rounded: it follows from NIST Special Publication 811. The SI unit: one joule every second.
Factor checked against the defining standard · How we check
- Watts × 1000
1 * 10001,000 mW
1 watt in every power unit
| Unit | Value | Exact factor |
|---|---|---|
| horsepower | 0.00134102209 hp | × 0.0013410220896 |
| metric horsepower | 0.001359621617 PS | × 0.0013596216173 |
| watts (as entered) | 1 W | — |
| kilowatts | 0.001 kW | × 0.001 |
| milliwatts | 1,000 mW | × 1,000 |
| megawatts | 0.000001 MW | × 0.000001 |
| tons of refrigeration | 0.0002843451361 TR | × 0.000284345136094 |
| BTU per hour | 3.412141633 BTU/h | × 3.41214163313 |
Factors are entered by hand from NIST Special Publication 811 rather than derived from a units library, so the ones that terminate are exact rather than rounded.
How do you convert watts to milliwatts? The converter and the working
- 1.Take the measurement in watts.
- 2.Multiply by 1000 — that is how many milliwatts fit in one watt.
- 3.To go back the other way, divide by 1000, or multiply by 0.001.
Worked example: 25 watts to milliwatts
- Formula
- W × 1000 = mW
- Arithmetic
- 25 × 1000 = 25,000 mW
- Answer
- 25 W = 25,000 mW
The factor is exact, so this figure is exact too — only the display is rounded.
Watts to milliwatts conversion table
| Watts | Milliwatts |
|---|---|
| 1 W | 1,000 mW |
| 2 W | 2,000 mW |
| 3 W | 3,000 mW |
| 4 W | 4,000 mW |
| 5 W | 5,000 mW |
| 6 W | 6,000 mW |
| 7 W | 7,000 mW |
| 8 W | 8,000 mW |
| 9 W | 9,000 mW |
| 10 W | 10,000 mW |
| 12 W | 12,000 mW |
| 15 W | 15,000 mW |
| 20 W | 20,000 mW |
| 25 W | 25,000 mW |
| 50 W | 50,000 mW |
| 100 W | 100,000 mW |
| 200 W | 200,000 mW |
| 300 W | 300,000 mW |
| 500 W | 500,000 mW |
| 1000 W | 1,000,000 mW |
| 2000 W | 2,000,000 mW |
| 5000 W | 5,000,000 mW |
| 10000 W | 10,000,000 mW |
What is a watt?
The SI unit: one joule every second. A watt is a rate, not an amount, which is the distinction between it and the watt-hour on your electricity bill.
What is a milliwatt?
A thousandth of a watt. Radio transmit power, laser output and audio signal levels are all quoted in it, and dBm is referenced to exactly one.
How many milliwatts are in a watt?
One watt is 1000 milliwatts, exactly. Going the other way, one milliwatt is 0.001 watts. Both figures come from the same defined relation rather than from a measurement, which is why they are the same today as they were in 1959.
Every power unit here
The whole group — 8 units with their symbols and the size of each one in watts — is on the conversion index, along with every pair it makes. The table above already gives each of them relative to a watt.
Source: NIST Special Publication 811 — mechanical horsepower is 550 ft·lbf/s exactly
Cite this page
- APA
- Rule Calculator. (2026). Convert Watts to milliwatts. Rule Calculator. https://rulecalculators.com/convert/watt-to-milliwatt
- MLA
- "Convert Watts to milliwatts." Rule Calculator, August 16, 2026, https://rulecalculators.com/convert/watt-to-milliwatt.
- Chicago
- Rule Calculator. "Convert Watts to milliwatts." Rule Calculator. Last reviewed August 16, 2026. https://rulecalculators.com/convert/watt-to-milliwatt.
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Questions people actually ask
- How many milliwatts are in a watt?
- 1000. A thousandth of a watt. Radio transmit power, laser output and audio signal levels are all quoted in it, and dBm is referenced to exactly one.
- How do I convert milliwatts back to watts?
- Divide by 1000, or multiply by 0.001 — they are the same operation.
Other power conversions
Milliwatts to watts — the same conversion the other way.