Power Calculator
Calculate electrical power (watts) from voltage, current, and power factor.
Calculate Electrical Power
Common Power Calculations
Click on these links to see instant calculations with common values:
Understanding Electrical Power
Electrical power is the rate at which electrical energy is transferred by an electric circuit. It is measured in watts (W).
Formulas
Power (P) = Volts (V) × Current (I)
For AC Single-Phase Circuits:
Power (P) = Volts (V) × Current (I) × Power Factor (PF)
For AC Three-Phase Circuits:
Power (P) = √3 × Volts (V) × Current (I) × Power Factor (PF)
Where:
• P = Power in Watts
• V = Voltage in Volts
• I = Current in Amperes
• PF = Power Factor (between 0 and 1)
• √3 ≈ 1.732
Key Concepts
- Watt (W): The unit of real power.
- Volt (V): The unit of electric potential difference.
- Ampere (A): The unit of electric current.
- Power Factor (PF): The ratio of real power to apparent power in AC circuits.
Typical Appliance Power Consumption
| Appliance | Typical Power (Watts) |
|---|---|
| LED Light Bulb | 5 - 15 |
| Laptop | 50 - 100 |
| Desktop Computer | 100 - 300 |
| Refrigerator | 100 - 400 |
| Microwave Oven | 600 - 1500 |
| Electric Kettle | 1500 - 3000 |
| Central Air Conditioner | 2000 - 5000 |
Frequently Asked Questions
What is the difference between real power and apparent power?
Real power (watts) is the power that actually performs work in a circuit. Apparent power (VA or kVA) is the total power supplied, including both real power and reactive power. Reactive power does not perform work but is necessary for the operation of inductive and capacitive components.
Why is power factor important in power calculations?
Power factor accounts for the efficiency of power usage in AC circuits. A low power factor means that a larger apparent power is needed to deliver the same amount of real power, leading to higher currents and potential inefficiencies.