Electrical Power Calculator

Online calculator for the relationship between power, voltage, and current

Calculation

Result
Power:
Voltage:
Current:


Good to know

What is electrical power?

Electrical power describes the relationship between voltage and current. It is measured in watts (W) and indicates how much energy is converted per unit time.

Important units
  • Power \((P)\): W, kW, MW, GW, mW
  • Voltage \((U)\): V, kV, mV, µV
  • Current \((I)\): A, kA, mA, µA
Basic formula
\[P = U \times I\]
Power = Voltage × Current
Alternative formulas
\[P = \frac{U^2}{R}\]
\[P = I^2 \times R\]
\[P = U \times I \times \cos(\phi)\] (AC)

Formulas for electrical power

Electrical power describes the relationship between electrical voltage and current. It is calculated using the basic formula and indicates how much electrical energy is converted per unit time.

Calculate power

\[\text{Power} = \text{Voltage} \times \text{Current}\] \[P = U \times I\]

Unit: Watts (W)

Calculate voltage

\[U = \frac{P}{I}\]

Unit: Volt (V)

Calculate current

\[I = \frac{P}{U}\]

Unit: Ampere (A)

Additional formulas

If the resistance \(R\) or other values are known, there are alternative formulas:

Using Ohm's law:
\[P = \frac{U^2}{R}\]
\[P = I^2 \times R\]
For alternating current (AC):
\[P = U \times I \times \cos(\phi)\]

\(\cos(\phi)\) = Power factor

Variable legend

  • \(P\): Electrical power in watts (W)
  • \(U\): Voltage in volts (V)
  • \(I\): Current in amperes (A)
  • \(R\): Resistance in ohms (Ω)
  • \(\phi\): Phase angle for AC
  • \(\cos(\phi)\): Power factor (0-1)

Practical example

Example: Lamp power

A lamp is connected to a voltage of 230 V and draws a current of 2 A. What is the power?

Given:

  • Voltage: \(U = 230 \text{ V}\)
  • Current: \(I = 2 \text{ A}\)

Calculation:

\[P = U \times I = 230 \text{ V} \times 2 \text{ A} = 460 \text{ W}\]

The lamp has a power of 460 watts.

Power classes
Household appliances:
LED lamp: 5-15 W
Laptop: 50-100 W
Refrigerator: 100-200 W
Microwave: 700-1200 W
Industrial applications:
Electric motor: 1-100 kW
Industrial furnace: 10-500 kW
Power plant: 100 MW - 1 GW
Unit conversions
Power units:
1 kW = 1,000 W
1 MW = 1,000 kW
1 GW = 1,000 MW
1 W = 1,000 mW
Relationship to energy:
1 W = 1 J/s
1 kWh = 3,600,000 J
1 PS ≈ 736 W
1 hp ≈ 746 W

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Battery Capacity  •  Capacitor Capacitance  •  Decibel, votage, power converter  •  Decibel - factor converter  •  Electric Power  •  Electric Energy  •  Electric Charge  •  Electrostatic force, Coulombs Law  •  Internal resistance of a power source  •  Ohm's law and power  •  Table of temperature coefficients  •  Temperature drift of resistance  •  Voltage drop  •  Wire resistance  •