Watts to Kilowatts Converter

Divide watts by 1,000. The SI prefix kilo means exactly 10^3, so 1 kW = 1,000 W by definition, not by measurement. A 1,500 W microwave is 1.5 kW. A 7,200 W EV charger is 7.2 kW. Going the other way, multiply kilowatts by 1,000 to get watts. The same decimal rule applies all the way up the ladder: 1 MW = 1,000 kW = 1,000,000 W, and 1 GW = 1,000 MW = 1 billion W. There are no binary prefixes for power because watts are an SI unit, not a counted quantity like bytes, so the OS-vs-vendor 1,024 vs 1,000 confusion you see with storage does not apply here.

It depends which horsepower. The mechanical horsepower used in the US and most SAE engine ratings is exactly 745.6999 W, so 1 hp = 0.7457 kW. James Watt defined it in 1782 as 33,000 ft-lbf per minute (the rate at which a strong dray horse could lift coal out of a mine). The metric horsepower used in continental Europe (PS in German, ch in French, CV in Italian and Spanish) is defined as 75 kgf-m/s, which works out to exactly 735.49875 W, so 1 PS = 0.7355 kW. The two differ by about 1.4 percent, which is why a 200 hp US car is roughly 203 PS on a European spec sheet. UK car ratings have used mechanical hp since 1973; before that they used the old RAC tax horsepower, which was a separate formula based on cylinder bore and is not a power unit at all.

EU regulations require kW on the nameplate, but PS dominates marketing because customers and journalists know what 200 PS feels like in a way they do not yet feel kW. Inside the regulation (UNECE R85 and EU 1230/2012), every new car must list power in kW; PS is allowed as an additional unit. So a Volkswagen Golf GTI is typed as 180 kW (245 PS); the dealer brochure leads with the 245 PS figure. The conversion is fixed: divide PS by 1.36 to get kW, or multiply kW by 1.36 to get PS. US car magazines almost always show mechanical hp (1 hp = 0.7457 kW), so a 245 PS Golf converts to about 241 hp, which is the number Car and Driver would print.

Useful reference points, all in real power (watts, not VA). LED bulb: 8 to 12 W. Phone charger: 5 to 25 W. Laptop: 30 to 100 W. Refrigerator: 100 to 200 W (averaged, with brief startup spikes). Window AC: 500 to 1,500 W. Microwave: 1,000 to 1,800 W. Hair dryer: 1,500 to 2,000 W. Electric kettle: 1,500 W. Toaster oven: 1,200 to 1,800 W. Electric dryer: 3,000 to 6,000 W (5 kW typical). Tankless electric water heater: 18,000 to 36,000 W (18 to 36 kW). Level 2 EV charger: 7,200 to 11,000 W (7.2 to 11 kW). Whole-house instantaneous peak draw is usually 5 to 15 kW; the 200 A service feeding most US single-family homes can supply 240 V x 200 A = 48,000 W (48 kW) for short bursts, but the standing average is closer to 1 to 2 kW.

Because kW measures power (the rate of energy use) and kWh measures energy (the total amount used over time). They are different quantities: energy = power x time. A 1,000 W (1 kW) heater running for 1 hour consumes 1 kWh of energy. The same heater running for 30 minutes consumes 0.5 kWh. The utility cannot bill you for power alone because how long a load runs matters as much as how big it is: a 100 W bulb left on for 24 hours uses 2.4 kWh, while a 2,400 W microwave run for 1 minute uses only 0.04 kWh. To estimate cost, multiply the device's kilowatts by the hours per day it runs by your rate per kWh: a 1.5 kW space heater on 8 hours a day at 0.15 dollars per kWh costs 1.5 x 8 x 0.15 = 1.80 dollars per day.