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What is a watt?

The SI power unit — 1 joule per second

Definition

The watt is the SI unit of power — 1 joule per second. Named after James Watt. Common examples: LED bulb 5–10 W, laptop 45–100 W, kettle 2000–3000 W, car engine 50,000+ W.

Common uses

  • Light-bulb and appliance ratings
  • Scientific and engineering power specs
  • Radio and electronics power

🌍 Real-world scale

LED bulb: 5–10 W. Laptop: 45 W. Kettle: 2200 W. Oven: 2000 W. Sun per m² on Earth: 1361 W/m².

Convert from watts

7 conversions
Watt to Kilowatt1 W = 0.001 kWWatt to Megawatt1 W = 1.0000e-6 MWWatt to Mechanical Horsepower1 W = 0.001341 hpWatt to Metric Horsepower1 W = 0.00136 PSWatt to BTU per Hour1 W = 3.41214 BTU/hWatt to Foot-Pound per Second1 W = 0.7376 ft·lbf/sWatt to Volt-Ampere1 W = 1 VA

Convert to watts

7 conversions
Kilowatt to Watt1 kW = 1,000 WMegawatt to Watt1 MW = 1,000,000 WMechanical Horsepower to Watt1 hp = 745.7 WMetric Horsepower to Watt1 PS = 735.499 WBTU per Hour to Watt1 BTU/h = 0.2931 WFoot-Pound per Second to Watt1 ft·lbf/s = 1.35582 WVolt-Ampere to Watt1 VA = 1 W

Tips

  • 1 W = 1 J/s = 1 V × 1 A (for DC).
  • LED lighting: 10× more efficient than incandescent.
  • For home appliances, rating × hours used = kWh.

Common mistakes

  • Confusing watts (power) with joules (energy).
  • Assuming "100 W bulb" for LED — old incandescent rating.
  • Mixing W with V or A — different quantities.

FAQ about the watt

What is a watt?
The watt is the SI unit of power — 1 joule per second. Named after James Watt. Common examples: LED bulb 5–10 W, laptop 45–100 W, kettle 2000–3000 W, car engine 50,000+ W.
Where is the watt used?
The watt is commonly used for: Light-bulb and appliance ratings; Scientific and engineering power specs; Radio and electronics power.
What is an example of a watt in real life?
LED bulb: 5–10 W. Laptop: 45 W. Kettle: 2200 W. Oven: 2000 W. Sun per m² on Earth: 1361 W/m².
What category does the watt belong to?
The watt is a unit of power, part of the 8-unit power category on UnitConv.
How accurate are watt conversions?
All conversion factors follow NIST and BIPM international standards to 8 significant figures — the highest practical accuracy.
Explore all 8 power units and their conversions.⚡ Power hub →