Watts Converter
Convert Watts (W) to any other power unit. The table below gives the exact figure for each unit, and every conversion is worked from the same engine as the converter.
What watts convert to
One W in every other power unit.
| Unit | 1 W | Reverse |
|---|---|---|
| Milliwatts | 1,000 mW | 0.001 W |
| Kilowatts | 0.001 kW | 1,000 W |
| Megawatts | 1e-6 MW | 1,000,000 W |
| Horsepower (mechanical) | 0.001341 hp | 745.699872 W |
| Metric horsepower | 0.00136 PS | 735.49875 W |
| BTU per hour | 3.412142 BTU/h | 0.293071 W |
Multiply a watts figure by the figure in the second column to get the unit in the first, or multiply by the third column to go the other way.
Watts conversion reference
Watts to Milliwatts
One watts is 1,000 milliwatts, and one milliwatts is 0.001 watts.
A milliwatt is one thousandth of a watt. It is used for small electronics, radio transmission power and laser pointers; an indicator LED draws a few milliwatts.
- 1 W= 1,000 mW
- 5 W= 5,000 mW
- 10 W= 10,000 mW
Watts to Kilowatts
One watts is 0.001 kilowatts, and one kilowatts is 1,000 watts.
A kilowatt is 1,000 watts. It is the usual unit for appliance ratings, generators, inverters and household electricity demand.
- 1 W= 0.001 kW
- 5 W= 0.005 kW
- 10 W= 0.01 kW
Exactly 1,000 watts make one kilowatt, written kW. This is the multiple that electrical equipment ratings use, and it equals one thousand joules of energy transferred per second.
Domestic appliance labels, generator sets, inverters, solar arrays and electric motors are all rated in kilowatts. Household demand and the capacity of a standby generator are usually quoted this way.
Watts to Megawatts
One watts is 1e-6 megawatts, and one megawatts is 1,000,000 watts.
A megawatt is 1,000 kilowatts. It is used for power stations, industrial loads and grid capacity, where large generator sets run into the megawatts.
- 1 W= 1e-6 MW
- 5 W= 5e-6 MW
- 10 W= 1e-5 MW
A megawatt is 1,000 kilowatts, or one million watts, and it carries the symbol MW. Power at this scale is quoted in megawatts because a figure in kilowatts would run to several digits.
Grid-scale generating stations, industrial plants, large data centres and utility-scale solar farms are described in megawatts of capacity. Transmission and distribution planning also uses the unit for load forecasts.
Watts to Horsepower (mechanical)
One watts is 0.001341 horsepower (mechanical), and one horsepower (mechanical) is 745.699872 watts.
Mechanical horsepower is 745.7 watts, the unit used for engine and motor output in the United States and UK. It is a different size from metric horsepower.
- 1 W= 0.001341 hp
- 5 W= 0.006705 hp
- 10 W= 0.01341 hp
Mechanical horsepower is exactly 745.7 watts, and metric horsepower is exactly 735.49875 watts. The two definitions differ by about 1.4 percent, so a figure carries a larger number in mechanical horsepower.
Vehicle engine output, pump and compressor motors, and agricultural machinery are commonly rated in horsepower. Metric horsepower is used for engine figures in much of Europe and Asia, while mechanical horsepower dominates in the United States.
Watts to Metric horsepower
One watts is 0.00136 metric horsepower, and one metric horsepower is 735.49875 watts.
Metric horsepower (PS) is 735.49875 watts, used for vehicle engine ratings across much of Europe and Asia. It is slightly smaller than mechanical horsepower.
- 1 W= 0.00136 PS
- 5 W= 0.006798 PS
- 10 W= 0.013596 PS
Watts to BTU per hour
One watts is 3.412142 btu per hour, and one btu per hour is 0.293071 watts.
One BTU per hour is 0.29307107 watts. It is used for air-conditioning and heating capacity, where '12,000 BTU' means roughly 3.5 kW.
- 1 W= 3.412142 BTU/h
- 5 W= 17.060708 BTU/h
- 10 W= 34.121416 BTU/h
One BTU per hour is exactly 0.29307107017222 watts, because one BTU is exactly 1,055.05585262 joules and an hour holds 3,600 seconds. The symbol is BTU/h.
Air conditioners, heat pumps, furnaces and chillers are rated in BTU per hour, and the figure on a room air conditioner describes its cooling capacity. Heating and cooling engineering uses the same unit for equipment sizing.
What watts are used for
The watt is the SI unit of power: one joule per second. It is used for light bulbs, small appliances and solar panel ratings; an LED bulb is typically 5 to 15 watts.
The watt is the SI unit of power: one joule of energy transferred each second. Its symbol is W, and it is the base from which every larger power unit is built.
Watt ratings appear on light bulbs, televisions, kettles, solar panels, inverters and small generators. Physics and engineering use the watt for every rate of energy transfer, from a laser to a motor.
Because power is a rate and energy is an amount, a watt multiplied by a duration gives energy in joules or watt-hours. Metric steps above the watt are exact powers of one thousand.
A frequent error treats the watt as a quantity of energy, so an appliance rating is read as consumption. Power needs a time period before it becomes an amount of energy.
Watts suit appliance and electronics figures, kilowatts suit generators, inverters and solar arrays, and megawatts suit grid capacity. Milliwatts cover indicator lights and small sensors. Reading a generator rating in watts rather than kilowatts multiplies the number by a thousand and misstates the scale.
Metric power conversions are exact. Check whether a horsepower figure is mechanical or metric before comparing two engines.
Within the metric units a power conversion is a power of a thousand: watts to kilowatts, kilowatts to megawatts, and back. Those pairs are decimal shifts and a reader can do them without a converter.
Anything involving horsepower is a multiplication by a definition rather than a shift, and there are two definitions. Mechanical horsepower is exactly 745.7 watts and metric horsepower exactly 735.49875 watts, so the same engine carries a larger figure in mechanical horsepower than in metric.
When checking a power conversion, convert to watts first, because every unit in this dimension is defined against the watt and the intermediate value makes the comparison obvious. The trap is comparing a horsepower figure with a kilowatt figure without establishing which horsepower was quoted.
Tanzania reference points
Real quantities, converted into watts.
Tanzania's installed electricity generation capacity
2,881.332 MW = 2,881,332,000 W
EWURA reports 2,842.96 MW on the main grid and 38.372 MW off-grid, with TANESCO holding 92.31% of it. Installed capacity is what the country could generate at once, not what it generates on an average day.
Source: EWURA Fact Sheet — electricity sub-sector (installed capacity) · verified 2026-09-14
Watts conversion tables
Watts to Milliwatts
| Watts (W) | Milliwatts (mW) |
|---|---|
| 1 | 1,000 |
| 2 | 2,000 |
| 3 | 3,000 |
| 4 | 4,000 |
| 5 | 5,000 |
| 10 | 10,000 |
| 25 | 25,000 |
| 50 | 50,000 |
| 100 | 100,000 |
Watts to Kilowatts
| Watts (W) | Kilowatts (kW) |
|---|---|
| 1 | 0.001 |
| 2 | 0.002 |
| 3 | 0.003 |
| 4 | 0.004 |
| 5 | 0.005 |
| 10 | 0.01 |
| 25 | 0.025 |
| 50 | 0.05 |
| 100 | 0.1 |
Watts to Megawatts
| Watts (W) | Megawatts (MW) |
|---|---|
| 1 | 1e-6 |
| 2 | 2e-6 |
| 3 | 3e-6 |
| 4 | 4e-6 |
| 5 | 5e-6 |
| 10 | 1e-5 |
| 25 | 2.5e-5 |
| 50 | 5e-5 |
| 100 | 1e-4 |
Related calculators
Try these calculators that use power measurements.