This page converts non-negative real power only. It does not convert apparent power in VA, logarithmic dBm, energy in mWh, device runtime, or measurement uncertainty.
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Use the focused mW-to-W conversion or reverse it instantly. One milliwatt is exactly one-thousandth of a watt under the SI decimal-prefix system.
1 mW = 0.001 W
Use 5,000 mW.
5,000 × 0.001 = 5.
5,000 mW = 5 W.
| Milliwatts (mW) | Watts (W) |
|---|---|
| 1 mW | 0.001 W |
| 10 mW | 0.01 W |
| 100 mW | 0.1 W |
| 500 mW | 0.5 W |
| 1,000 mW | 1 W |
| 2,000 mW | 2 W |
| 5,000 mW | 5 W |
| 10,000 mW | 10 W |
| 100,000 mW | 100 W |
| 1,000,000 mW | 1,000 W |
Device-power notation guide
Milliwatts are suited to device-scale linear power budgets, where lowercase m, careful decimal handling, and separation from dBm or energy are essential.
Step-by-step guide · Device-power notation guide
Two hundred fifty milliwatts divided by 1,000 is 0.25 W. A result of 250 W would omit the milli prefix entirely.
Five thousand milliwatts divided by 1,000 is 5 W. The same equality in reverse is 5 W × 1,000 = 5,000 mW.
One milliwatt is 1,000 microwatts. If the values are consistently far below 0.001 mW, a smaller SI prefix may communicate them more clearly than repeated leading zeros.
The lowercase prefix symbol m means milli, or 10⁻³. Uppercase M means mega, or 10⁶. Attached to the uppercase watt symbol W, they form mW and MW: two valid units separated by nine powers of ten. One megawatt equals one billion milliwatts, so autocorrecting, capitalizing, or lowercasing a symbol can change the reported magnitude catastrophically.
NIST's SI writing guidance also keeps the prefix attached to the unit symbol and places a space between the numeric value and that symbol: 250 mW, not 250m W. The unit name watt is lowercase when written out, while W is uppercase because it is derived from a person's name. These conventions are functional safeguards for tables, diagrams, and copied specifications.
The prefix factor is exact, making a few anchor values useful for checking direction and decimal placement.
Two hundred fifty milliwatts divided by 1,000 is 0.25 W. A result of 250 W would omit the milli prefix entirely.
Five thousand milliwatts divided by 1,000 is 5 W. The same equality in reverse is 5 W × 1,000 = 5,000 mW.
One milliwatt is 1,000 microwatts. If the values are consistently far below 0.001 mW, a smaller SI prefix may communicate them more clearly than repeated leading zeros.
For forty identical modules at 75 mW each, keep the component rating in milliwatts and multiply first: 40 × 75 mW = 3,000 mW. The combined linear power is then 3 W. This source-unit-first workflow is easier to review than converting each module to a short decimal watt display and adding already rounded values.
A useful budget must still define the operating condition. Typical, idle, transmit, startup, and maximum ratings may describe different states, and simply adding unlike states can overstate or understate the intended scenario. The unit converter preserves the magnitude relationship but does not decide which device ratings belong in a simultaneous load model.
Several neighboring electrical quantities require more than multiplying or dividing by 1,000.
A dBm value is a logarithmic power ratio referenced to one milliwatt. It cannot be changed into watts by treating the dBm number itself as a linear mW amount.
Use the volt-amps calculator when those electrical quantities and power factor form the actual problem. The milliwatt page has no voltage or current input to infer them.
Use the voltage drop calculator for conductor size, length, current, material, and circuit configuration. A converted power value alone is not a voltage-drop estimate.
When the source is genuinely in millions of watts, use the megawatt calculator. It emphasizes system-scale aggregation and the distinction between MW power and MWh energy rather than device-scale notation.