Watts to Kilowatts
Convert watts to kilowatts for electricity billing, solar sizing, and appliance comparison. kW = W ÷ 1,000 — enter any watt value for instant kilowatt conversion.
Enter your values above to see the results.
Tips & Notes
- ✓Electricity bills charge in kilowatt-hours (kWh). Energy = Power (kW) × Time (hours). A 2,500 W electric oven running 1 hour = 2.5 kW × 1 hr = 2.5 kWh. At $0.15/kWh: 2.5 × 0.15 = $0.375 per hour of use.
- ✓Home electricity demand: a typical US home uses 10,500 kWh/year = 1.2 kW average. Peak demand includes: central AC 3,500 W = 3.5 kW; electric water heater 4,000 W = 4 kW; electric range 7,200 W = 7.2 kW; EV charger (level 2) 7,200 W = 7.2 kW.
- ✓Solar panel output is rated in watts (W) but production is measured in kilowatt-hours. A 400 W panel in 5 peak-sun-hours/day produces 400 × 5 = 2,000 Wh = 2.0 kWh/day = 730 kWh/year.
- ✓Motor ratings use both watts and kilowatts. Small motors: 250 W = 0.25 kW; fractional horsepower. Medium: 2,200 W = 2.2 kW = 3 hp. Large industrial: 75,000 W = 75 kW = 100.6 hp.
- ✓Power generation: a nuclear power plant generates 1,000-1,600 MW = 1,000,000-1,600,000 kW. A large wind turbine: 2,000-5,000 kW = 2-5 MW. Home solar: 5,000-10,000 W = 5-10 kW installed capacity.
Common Mistakes
- ✗Confusing watts (power rate) with watt-hours (energy) — a 100-W bulb consumes power at 100 W continuously. Running it for 10 hours uses 100 W × 10 h = 1,000 Wh = 1 kWh of energy. Power is the rate; energy is the total.
- ✗Adding kilowatts and watts without converting — "my solar panel makes 0.4 kW and my inverter uses 25 W" — to compare: 0.4 kW = 400 W, so net output = 400 − 25 = 375 W = 0.375 kW. Never mix units in the same calculation.
- ✗Using kW ratings for sizing without checking duty cycle — an appliance rated 3,500 W (3.5 kW) may not run continuously. An AC compressor cycles on/off; effective demand may be 1.5-2.0 kW averaged over time. Circuit sizing uses peak demand; billing uses average energy.
- ✗Confusing kW (power) with kWh (energy) on electricity bills — bills charge for kWh (energy used), not kW (power). A 3 kW heater running 4 hours uses 12 kWh. At $0.15/kWh: cost = $1.80. The kW rating alone does not determine cost — usage time must be included.
- ✗Neglecting power factor for AC circuits — a motor rated 2 kW may draw 2,400 VA (volt-amperes) at 0.83 power factor. The wiring and breaker must be sized for VA, but the electricity bill is based on kWh (real power). This distinction matters for industrial power factor correction.
Watts to Kilowatts Overview
Watts and kilowatts measure power — the rate at which energy is consumed or produced. The practical world of electricity billing, solar sizing, and appliance comparison operates in kilowatts and kilowatt-hours. Converting from watts is straightforward (÷ 1,000) but the implications span from individual device comparison to national grid planning.
Watts to kilowatts formula:
kW = W / 1,000 | Energy: kWh = kW × hours = (W/1,000) × hours
EX: Electric kettle 2,200 W → 2.2 kW. Boiling water 5 min/day = 5/60 = 0.0833 hr → Energy = 2.2 × 0.0833 = 0.183 kWh/day. Annual cost at $0.15: 0.183 × 365 × $0.15 = $10.03/yearElectricity cost calculation:
Daily cost = (W / 1,000) × hours/day × rate ($/kWh) | Monthly = daily × 30
EX: Central AC 3,500 W running 8 hours/day at $0.15/kWh → daily = (3,500/1,000) × 8 × 0.15 = 3.5 × 8 × 0.15 = $4.20/day → $126/month → $504 for a 4-month cooling seasonCommon appliances — watts and kilowatts:
| Appliance | Watts (W) | Kilowatts (kW) | Annual Cost ($0.15/kWh) |
|---|---|---|---|
| LED bulb (typical use) | 10 W | 0.010 kW | $4.38/yr (8 hr/day) |
| Laptop computer | 50 W | 0.050 kW | $21.90/yr (8 hr/day) |
| Refrigerator | 150 W avg | 0.150 kW | $197.10/yr (24 hr/day) |
| Electric water heater | 4,000 W | 4.000 kW | $436.80/yr (2 hr/day) |
| Central AC | 3,500 W | 3.500 kW | $613.20/yr (8 hr × 4 mo) |
| Level 2 EV charger | 7,200 W | 7.200 kW | $394.20/yr (1 hr/day avg) |
| Power Level | Watts | Kilowatts | Example |
|---|---|---|---|
| Micro-scale | 0.001-1 W | 0.000001-0.001 kW | Smart sensor, LED indicator |
| Small device | 5-100 W | 0.005-0.1 kW | Phone charger, LED bulb |
| Household appliance | 500-5,000 W | 0.5-5 kW | Microwave, AC unit |
| Residential solar | 5,000-15,000 W | 5-15 kW | Rooftop PV system |
| Commercial/industrial | 50,000-1,000,000 W | 50-1,000 kW | Office building, factory |
Frequently Asked Questions
Divide watts by 1,000. Examples: 100 W = 0.1 kW; 500 W = 0.5 kW; 1,000 W = 1.0 kW; 2,500 W = 2.5 kW; 5,000 W = 5.0 kW; 10,000 W = 10 kW; 100,000 W = 100 kW; 1,000,000 W = 1,000 kW = 1 MW. Multiply kilowatts by 1,000 to get watts. Simple rule: move the decimal point three places left to convert W to kW.
Step 1: convert watts to kilowatts (divide by 1,000). Step 2: multiply by hours of use to get kWh. Step 3: multiply kWh by your electricity rate ($/kWh). Formula: Cost = (W/1,000) × hours × rate. Example: 1,500 W space heater, 8 hours/day, $0.15/kWh. Cost/day = (1,500/1,000) × 8 × 0.15 = 1.5 × 8 × 0.15 = $1.80/day = $54/month = $648/year. A 60 W LED TV 4 hours/day: (60/1,000) × 4 × 0.15 = $0.036/day = $13.14/year.
Appliance power consumption: LED bulb 8-10 W (0.008-0.010 kW); laptop 30-65 W (0.030-0.065 kW); desktop computer 150-300 W (0.15-0.3 kW); refrigerator 100-200 W average (0.1-0.2 kW); microwave oven 700-1,200 W (0.7-1.2 kW); dishwasher 1,200-1,500 W (1.2-1.5 kW); clothes dryer 5,000-6,000 W (5-6 kW); electric stove top (single burner) 1,200-2,400 W (1.2-2.4 kW); central AC 2,000-5,000 W (2-5 kW); electric water heater 3,500-4,500 W (3.5-4.5 kW); EV charger (Level 2) 7,200-9,600 W (7.2-9.6 kW).
Solar panels are rated in watts (peak); production is measured in kWh. Sizing calculation: (1) find daily kWh usage from electricity bill; (2) divide by average peak sun hours for your location; (3) result is required system kW; (4) divide by single panel wattage (W) to get number of panels. Example: 1,200 kWh/month usage ÷ 30 days = 40 kWh/day. Location gets 5 peak sun hours: 40 kWh/5 = 8.0 kW system needed. With 400 W panels: 8,000 W / 400 W = 20 panels. Account for 20-25% system losses: actual need 24-25 panels.
All measure power (rate of energy transfer), just at different scales: 1 kW = 1,000 W; 1 MW = 1,000 kW = 1,000,000 W; 1 GW = 1,000 MW. Applications by scale: W — individual devices (LED bulb 10 W, phone charger 20 W, laptop 50 W); kW — household systems (AC 3 kW, EV charger 7.2 kW, residential solar 10 kW); MW — power plants and industrial facilities (wind turbine 3 MW, hospital 2 MW, data center 20 MW); GW — large power plants and national grids (nuclear plant 1 GW, US peak summer demand 780 GW). Energy units scale similarly: Wh, kWh, MWh, GWh, TWh.
Electric vehicle charging levels and power: Level 1 (110V household outlet): 1,440 W = 1.44 kW — adds 4-5 miles of range per hour, best for overnight. Level 2 (240V dedicated circuit): 3,300-19,200 W = 3.3-19.2 kW — adds 10-60 miles per hour. Level 3 / DC Fast Charging (DCFC): 50,000-350,000 W = 50-350 kW — adds 100-200+ miles in 20-30 minutes. Tesla Supercharger V3: 250,000 W = 250 kW peak. Rivian R1T battery: 135,000 Wh = 135 kWh capacity. At $0.30/kWh DC fast charge rate: 135 kWh × $0.30 = $40.50 for a full charge from empty.