This free motor HP calculator works three ways: as an HP to kW converter, a kW to HP converter, and a motor power calculator that works out kW, HP and apparent kVA from voltage and current. Whether you are sizing a 3-phase induction motor, checking a nameplate rating, or estimating motor full load current, enter the numbers and read the result instantly — no sign-up.
How to convert HP and kW
Horsepower (HP) and kilowatts (kW) are both units of power, so converting between them is a single multiplication. The constant is 1 HP = 0.7457 kW (often rounded to 1 HP = 0.746 kW):
- HP to kW:
kW = HP × 0.7457. So 5 HP × 0.7457 = 3.73 kW, and 10 HP = 7.46 kW. - kW to HP:
HP = kW ÷ 0.7457. So 3.73 kW ÷ 0.7457 = 5 HP, and 7.5 kW = 10.06 HP.
This is the metric/mechanical horsepower used for motors in India and most of the world. The tool above flips between the two directions and recalculates the moment you type.
Calculate motor power from voltage & current
When you only know the supply voltage and the current the motor draws, you can work out its power directly. For a 3 phase motor power calculation the input (electrical) power is:
Input power (kW) = √3 × V × I × pf ÷ 1000
where V is the line voltage, I is the line current in amps, and pf is the power factor. For a single-phase motor, drop the √3: Input power (kW) = V × I × pf ÷ 1000.
Worked example: a 3-phase motor running at 415 V, drawing 10 A, with a power factor of 0.85:
P = √3 × 415 × 10 × 0.85 ÷ 1000 ≈ 6.11 kW input power.
That is the power drawn from the supply. The mechanical output (shaft) power is lower because of motor losses: at 90% efficiency, output = 6.11 × 0.90 ≈ 5.5 kW, which is about 7.4 HP. The apparent power (in kVA) ignores power factor: kVA = √3 × V × I ÷ 1000 ≈ 7.19 kVA. Run the numbers backwards from a target HP and you get the motor full load current you need to size cables and protection.
HP to kW quick chart
Common motor ratings converted with the 1 HP = 0.7457 kW constant:
| Horsepower (HP) | Kilowatts (kW) |
|---|---|
| 1 HP | 0.75 kW |
| 2 HP | 1.49 kW |
| 3 HP | 2.24 kW |
| 5 HP | 3.73 kW |
| 7.5 HP | 5.59 kW |
| 10 HP | 7.46 kW |
| 15 HP | 11.19 kW |
| 20 HP | 14.91 kW |
From motor specs to maintenance
A converter answers one line; running a factory means tracking those motors for their whole life. Inside OEMup ERP, motor HP/kW ratings, full-load current and supplier details live in the item master, so they flow straight into BOMs, costing, stock and GST invoices — and into maintenance schedules for the motors already running on your shop floor. No re-keying nameplate data into a dozen spreadsheets. Start a free trial and see motor-driven assemblies costed and tracked end to end.
Frequently asked questions
How many kW is 1 HP?
One mechanical (shaft) horsepower equals 0.7457 kW, commonly rounded to 0.746 kW. So a 1 HP motor is about 0.746 kW, 5 HP is about 3.73 kW, and 10 HP is about 7.46 kW. This calculator uses 1 HP = 0.7457 kW.
How do I convert HP to kW?
Multiply horsepower by 0.7457: 7.5 HP × 0.7457 = 5.59 kW. To convert kW to HP, divide by 0.7457: 5.59 kW ÷ 0.7457 = 7.5 HP. Switch the tool between HP → kW and kW → HP modes.
How do I calculate motor power from current?
For a 3-phase motor, input power (kW) = √3 × V × I × pf ÷ 1000. For single-phase, drop the √3. A 3-phase motor at 415 V, 10 A, pf 0.85 draws about 6.1 kW. Multiply by efficiency for output power, then divide by 0.7457 for HP.
What is the difference between input and output power?
Input (electrical) power is what the motor draws from the supply; output (shaft) power is the mechanical power delivered to the load. Output = input × efficiency, with the difference lost as heat. Motor HP ratings refer to output power.
Need more shop-floor tools? Browse all free calculators or size a pump with the Pump Power Calculator and track machine uptime with the OEE Calculator.
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