Aisha K.
Mar 12, 2026
Clean layout and the results update instantly. Exactly what I needed for a quick planning check.
Unit Converters
SI Watt Prefix Converter (mW, W, kW, MW, GW, TW)
to = from × 10^(fromExp − toExp) on watts.
Phone chargers in watts, homes in kilowatts, plants in megawatts, grids in gigawatts. A 1.5 kW kettle is 1,500 W. Terawatts show up in climate-scale diagrams, not in a breaker panel.
watts · 420 prefix pairs
watts
1,500 W
Multiply by 10^3. Same dimension; only the zeros move.
- You entered
- 1.5 kW
- Factor
- 10^3
- In scientific notation
- 1.500000e+3
Plain-English guide
Terms & how it works
Confused by a field? Read the short definitions here while you use the tool.
From prefix
The “From prefix” value used in this tool’s formula. Adjust it to see results update live.
How this calculator works
Phone chargers in watts, homes in kilowatts, plants in megawatts, grids in gigawatts. A 1.5 kW kettle is 1,500 W. Terawatts show up in climate-scale diagrams, not in a breaker panel. to = from × 10^(fromExp − toExp) on watts. Example: 1.5 kW → 1,500 W → 0.0015 MW. A 5 mW laser pointer is 0.005 W.
to = from × 10^(fromExp − toExp) on watts.
Example: 1.5 kW → 1,500 W → 0.0015 MW. A 5 mW laser pointer is 0.005 W.
When to use this SI Watt Prefix
Common use cases
- Phone chargers in watts, homes in kilowatts, plants in megawatts, grids in gigawatts. A 1.5 kW kettle is 1,500 W. Terawatts show up in climate-scale diagrams, not in a breaker panel.
- Sanity-check with this case: 1.5 kW → 1,500 W → 0.0015 MW. A 5 mW laser pointer is 0.005 W.
- The relationship is: to = from × 10^(fromExp − toExp) on watts.
Localized examples
- Unit Converters: the example on this page uses the same formula as the widget.
What you get
- Fields: From prefix
- to = from × 10^(fromExp − toExp) on watts.
- Example on the page: 1.5 kW → 1,500 W → 0.0015 MW. A 5 mW laser pointer is 0.005 W.
How to Convert SI Watt Prefix Step-by-Step
- 1Enter From prefix. Use the values you have, not a catalog average, unless that is all you know.
- 2to = from × 10^(fromExp − toExp) on watts.
- 3Worked case: 1.5 kW → 1,500 W → 0.0015 MW. A 5 mW laser pointer is 0.005 W.
- 4Check which dictionary the other person is using — US or UK, decimal or 1,024 — then trust the number.
Governing formula
to = from × 10^(fromExp − toExp) on watts.
1.5 kW → 1,500 W → 0.0015 MW. A 5 mW laser pointer is 0.005 W.
Example: set From prefix = 1.5, then read the result.
Variable definitions
- value
From prefix
The “From prefix” field. Default 1.5; typical range 0–1e+24.
- The conversion (to = from × 10^(fromExp − toExp) on watts.) does not pick US vs UK gallons, SI vs binary megabytes, or Mach at altitude for you. Read the footnote on the page.
- Nothing here is uploaded for the calculation itself.
Frequently Asked Questions
Kilowatt-hours need the energy page. Watts are the rate.
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- SI Henry Prefix ConverterPower inductors are millihenrys. RF chokes are microhenrys. A 1 H inductor is an audio-era doorstop. Scale the prefix; this is not an impedance-at-frequency calculator.
- SI Hertz Prefix ConverterAudio A4 is 440 Hz. FM radio lives in megahertz. Wi-Fi and CPUs argue in gigahertz. IR spectroscopy climbs into terahertz. Same hertz, different zeros. This grid also covers millihertz if you are watching a very slow oscillator.
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Reviews & Ratings
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4.8
out of 5.0
4 reviews
Daniel R.
Feb 28, 2026
Very usable on mobile. Would love a save/export option later, but the math feels solid.
Priya S.
Feb 3, 2026
The FAQ section answered my questions before I even had to search. Smooth dark mode too.
Marcus L.
Jan 19, 2026
Simple inputs, clear outputs. This replaced three bookmarks I used to juggle.
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