Electrical Energy Calculator

Online calculator for the relationship between energy, power, and time

Calculation

Result
Energy:
Power:
Time:

Good to know

What is electrical energy?

Electrical energy is the electrical power measured over a certain period of time. It can be specified in watt/second or kilowatt/hour.

Important units
  • Energy \((E)\): J, kWh, Wh
  • Power \((P)\): W, kW, MW, GW
  • Time \((t)\): s, min, h, days
Basic formula
\[E = P \times t\]
Energy = Power × Time
Example

A light bulb with \(100 \text{ W}\) burns for \(5 \text{ h}\):

\[E = 0.1 \text{ kW} \times 5 \text{ h} = 0.5 \text{ kWh}\]

Formulas for electrical energy

Electrical energy is the electrical power measured over a certain period of time. It can be specified in watt/second or kilowatt/hour. To calculate electrical energy, the following basic formulas are used:

Electrical energy

\[\text{Energy} = \text{Power} \times \text{Time}\] \[E = P \times t\]

If the power \(P\) is not given, it can be calculated using the formula:

\[E = U \times I \times t\]

Electrical power

\[P = \frac{E}{t}\]

Alternative formula with voltage and current:

\[P = U \times I\]

Time period

\[t = \frac{E}{P}\]

Variables and units

  • \(E\): Electrical energy (in joules \((J)\) or kilowatt hours \((kWh)\))
  • \(P\): Electrical power (in watts \((W)\) or kilowatts \((kW)\))
  • \(t\): Time (in seconds \((s)\) or hours \((h)\))
  • \(U\): Voltage (in volts \((V)\))
  • \(I\): Current (in amperes \((A)\))

Practical examples

Example 1: Light bulb

Power: \(100 \text{ W}\), Time: \(5 \text{ h}\)

\[E = 0.1 \text{ kW} \times 5 \text{ h} = 0.5 \text{ kWh}\]
Example 2: With voltage and current

Voltage: \(230 \text{ V}\), Current: \(2 \text{ A}\), Time: \(3 \text{ h}\)

\(P = 230 \text{ V} \times 2 \text{ A} = 460 \text{ W}\)
\(E = 460 \text{ W} \times 3 \text{ h} = 1.38 \text{ kWh}\)
Conversion factors
Energy units:
1 kWh = 1,000 Wh
1 kWh = 3,600,000 J
1 MWh = 1,000 kWh
Time units:
1 h = 60 min = 3,600 s
1 day = 24 h = 86,400 s
1 ms = 0.001 s

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