Volts to Horsepower Converter
A 230 V supply that pushes 10 amps through a motor delivers 2,300 watts of electrical power, which is about 3.08 horsepower.
Quick answer: Multiply the volts by the amps, then divide by 745.7. For example, 230 V at 10 A is 3.084 hp, 120 V at 15 A is 2.414 hp and 400 V at 25 A is 13.41 hp.
The volts to horsepower formula
Volts alone cannot become horsepower, because horsepower measures power and volts measure only electrical pressure. You also need the current in amps.
Power in watts is volts times amps. One mechanical horsepower is 745.69987 watts (Wikipedia: Horsepower).
Take 230 V at 10 A. 230 × 10 ÷ 745.7 gives 3.084 hp.
Take 120 V at 15 A. 120 × 15 ÷ 745.7 gives 2.414 hp.
Electrical input power in horsepower
This page treats the volts and amps as the electrical power going into a device. The result is the input in horsepower.
A real motor loses some power as heat, so the shaft output is lower than this number.
How to convert volts to horsepower step by step
- Enter the voltage in volts.
- Enter the current in amps.
- Read the power in horsepower.
- Check the last column for the same power in kilowatts.
Example 1: 230 V at 10 A
- Start with 230 V at 10 A.
- 230 × 10 ÷ 745.7 = 3.084.
- The electrical horsepower is 3.084 hp.
230 V at 10 A = 3.084 hp
Example 2: 120 V at 15 A
- Start with 120 V at 15 A.
- 120 × 15 ÷ 745.7 = 2.414.
- The electrical horsepower is 2.414 hp.
120 V at 15 A = 2.414 hp
Example 3: 400 V at 25 A
- Start with 400 V at 25 A.
- 400 × 25 ÷ 745.7 = 13.41.
- The electrical horsepower is 13.41 hp.
400 V at 25 A = 13.41 hp
For the shaft output of a motor, multiply the result by the efficiency, as a decimal.
volts to horsepower conversion table
| Supply | Horsepower | In kW |
|---|---|---|
| 12 V at 10 A | 0.1609 hp | 0.12 kW |
| 24 V at 20 A | 0.6437 hp | 0.48 kW |
| 48 V at 30 A | 1.931 hp | 1.44 kW |
| 120 V at 5 A | 0.8046 hp | 0.6 kW |
| 120 V at 15 A | 2.414 hp | 1.8 kW |
| 230 V at 10 A | 3.084 hp | 2.3 kW |
| 230 V at 16 A | 4.935 hp | 3.68 kW |
| 240 V at 20 A | 6.437 hp | 4.8 kW |
| 400 V at 25 A | 13.41 hp | 10 kW |
| 480 V at 50 A | 32.185 hp | 24 kW |
| 690 V at 100 A | 92.531 hp | 69 kW |
The highlighted row is the default of the calculator. The last column gives kW.
A quick mental shortcut for volts to horsepower
At 230 V, each amp is about 0.31 hp. So 10 A is about 3.1 hp.
At 120 V, each amp is about 0.16 hp. So 10 A is about 1.6 hp.
Why amps are needed
Volts tell you how hard the supply pushes. Amps tell you how much current flows. Power needs both.
A 230 V supply with no load draws no power at all.
Mechanical and electrical horsepower
Mechanical horsepower is 745.69987 W. The electrical horsepower used for motor ratings is 746 W (Wikipedia: Horsepower).
The difference is under 0.1 percent, so the result is the same for everyday work.
Input versus output
A motor that draws 2,300 W is not producing 3.0844 hp at the shaft. Some power is lost as heat.
At 90 percent efficiency the shaft output is about 2.7759 hp.
AC motors and power factor
On AC, real power is volts times amps times the power factor (Wikipedia: Power factor).
A motor at power factor 0.85 and 230 V with 10 A uses about 2.6217 hp of real power.
Low voltage DC examples
A 24 V motor that draws 20 A uses 480 W, or about 0.64369 hp.
There is no power factor on DC, so the formula is exact.
Going the other way
To get the current from horsepower, multiply by 745.7 and divide by the volts.
For 3.08 hp at 230 V the current is 9.9859 A.
Check your answer
Multiply your horsepower by 745.7. You should get the volts times the amps.
For 3.084 hp the result is 2,300 W, which equals 230 V times 10 A.
Metric horsepower
Metric horsepower is 735.49875 W. So 2,300 W is about 3.1271 metric hp, compared with 3.0844 mechanical hp.
If a European label shows PS or CV, use the metric figure.
Quick conversion answers
| Conversion | Result |
|---|---|
| 12 V at 5 A | 0.0805 hp |
| 24 V at 10 A | 0.3218 hp |
| 120 V at 10 A | 1.609 hp |
| 230 V at 20 A | 6.169 hp |
| 400 V at 40 A | 21.456 hp |
| 480 V at 60 A | 38.621 hp |
Where this conversion is used
Hobbyists size a motor from its voltage and current rating.
Electricians turn a nameplate into a rough horsepower figure.
Students practise the link between electrical and mechanical power.
Common mistakes to avoid
- Trying to convert volts alone. You must know the current as well.
- Reading input as output. The shaft horsepower is lower because of losses.
- Ignoring the power factor on AC. Real power is lower than volts times amps.
- Mixing up 735.5 and 745.7. Metric horsepower is 735.5 W, mechanical horsepower is 745.7 W.
Related converters
- Amps to horsepower
- Horsepower to watts
- Volts to megawatts
- Amps to watts
- kW to horsepower
- Tons to Amps
Frequently asked questions
Can I convert volts to horsepower directly?
No. You also need the current in amps.
How many watts is one horsepower?
Mechanical horsepower is 745.69987 W.
How many hp is 230 V at 10 A?
About 3.08 hp of electrical input.
Is this the shaft output of a motor?
No. Multiply by the efficiency to get the output.
Does power factor matter?
On AC it does. Real power is lower when the power factor is below 1.
What about metric horsepower?
It is 735.5 W, so the answer would be a little higher.
Sources
- Wikipedia: Horsepower (en.wikipedia.org)
- Wikipedia: Power factor (en.wikipedia.org)
- Wikipedia: Volt (en.wikipedia.org)
