Converting kilowatts starts with one question: are you comparing power, energy or current? A kilowatt is a unit of power. Horsepower is another power unit, while kWh and kJ measure energy. The difference between kW and kWh matters whenever time is involved. Calculating current also requires the supply voltage; kW alone is not enough.

Use the calculator below to convert power units in either direction, calculate energy over time, work out DC or AC current, or convert between kW and kVA with a known power factor. Decimal dots and decimal commas both work; leave out thousands separators.

How do you convert kW to horsepower?

For kilowatt-to-horsepower conversions, check the horsepower definition first. Mechanical hp is approximately 0.745700 kW. Metric horsepower, PS, is approximately 0.735499 kW. The calculator provides separate hp and PS options. If a rating says only “HP” or “horsepower,” confirm the manufacturer’s definition.

hp = kW ÷ 0.745699872
kW = hp × 0.745699872
For example, 2 mechanical hp is approximately 1.4914 kW. Treating 1 hp as 1 kW gives an incorrect result.

A rated kW figure on an electric motor usually describes mechanical output at the shaft. Changing that rating to hp does not reveal the motor’s electrical consumption. To calculate electrical input, include efficiency: P_input = P_shaft ÷ η. A motor delivering 7.5 kW at 90% efficiency needs about 8.333 kW of active electrical input at that operating point.

How much energy does a kW rating represent?

Power × time = energy. For constant power, E (kWh) = P (kW) × t (hours). A 2 kW load running for 3 hours uses 6 kWh. A 1 W load running for 1 hour uses 1 Wh, or 0.001 kWh. The hour is part of the energy unit; it is not a billing tariff.

A monthly consumption estimate needs operating hours and the number of operating days. Thermostats and speed controls can reduce average demand below the nameplate rating. An electricity meter records accumulated active energy. If you know the energy and elapsed time, calculate average kW = kWh ÷ hours; this does not reveal short peaks within that period.

How many amperes is a given kW load?

The ampere measures current. Converting kW to amperes requires voltage and the type of supply. Single-phase and three-phase supplies use different equations. For AC power, use RMS voltage and true power factor rather than assuming every load has PF = 1.

Steady DC: I (A) = 1000 × P (kW) ÷ V
Single-phase AC: I (A) = 1000 × P (kW) ÷ (V × PF)
Balanced three-phase AC: I (A) = 1000 × P (kW) ÷ (√3 × V_line-line × PF)

Here, P is active electrical input power. For single phase, use the voltage across the load; in a usual line-to-neutral connection, that is the line-to-neutral voltage. For three phase, enter line-to-line voltage and total three-phase power; the answer is line current. When converting watts to amperes, omit the factor of 1000 because the power is already in watts.

Example: a 2 kW input at 220 V and PF = 0.8 draws 2000 ÷ (220 × 0.8) ≈ 11.36 A on a single-phase supply. At 230 V, the corresponding result is about 10.87 A. The difference between 220 V and 230 V therefore changes the answer. A purely resistive AC load can have PF close to 1, but this assumption does not apply to every appliance.

Select “motor shaft output” to include motor efficiency. These equations describe the entered operating point; they do not predict starting current. Starting arrangements such as star–delta starting require the motor’s connection and manufacturer data to be considered separately.

What converts kW to kVA?

The difference between kW and kVA is active power versus apparent power. One kVA equals 1000 volt-amperes. At the same operating point, PF = kW ÷ kVA, so kVA = kW ÷ PF and kW = kVA × PF. For example, 10 kW of active electrical input at PF = 0.8 corresponds to 12.5 kVA.

The ratio of watts to volt-amperes is not efficiency or percentage load. Equal kW and kVA figures indicate PF = 1; they do not establish full-load operation. A transformer is commonly rated in kVA. When choosing a UPS, check both its kW and kVA limits. Do not infer one universal power factor from the UPS type.

Can kW be converted to BTU or kcal?

BTU and kcal measure energy; BTU/h and kcal/h measure power. You can convert kW directly to the hourly units. To calculate a total in BTU or kcal, include elapsed time. The following factors use the International Table (IT) definitions.

For example, 5 kW of thermal power is about 17060.71 BTU/h. Sustained for 2 hours, it represents about 34121.42 BTU of energy. Efficiency does not belong in a unit conversion; it belongs in a calculation relating input energy to useful output.

Cooling capacity does not equal electrical demand. A 12000 BTU/h air conditioner has approximately 3.517 kW of thermal cooling capacity. Its electrical input requires performance data or measurement for the same operating conditions. Converting BTU/h to kW changes the unit of that thermal capacity.

How do you calculate kJ from kW?

1 kW = 1 kJ/s. With time in seconds, use E (kJ) = P (kW) × t (seconds). With time in hours, use E (kJ) = P (kW) × t (hours) × 3600. A 100 kW load sustained for 2 hours therefore represents 200 kWh = 720000 kJ. The calculator accepts hours, minutes or seconds.

Why might the measured result differ?

Voltage, load, power factor and efficiency can change during operation. For AC measurements, understand True RMS and choose suitable instruments. An ammeter measures current and a voltmeter measures voltage; calculating active AC power also requires PF. Supply frequency does not add a factor to an hp-to-kW conversion, although it can affect how a motor operates.

Voltage drop can change the voltage at the load. Calculated current alone does not select a cable size or protective device. A socket’s load capacity depends on the ratings of the socket, wiring, connections and circuit protection together.