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)
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.
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.
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. Scenario: 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.
Scenario: 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 scenario: 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.
- Scenario 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
- 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.
- 3Scenario: 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.
1.5 kW → 1,500 W → 0.0015 MW. A 5 mW laser pointer is 0.005 W.
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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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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