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Ohm’s law
Find current and power from voltage and resistance.
Calculators / Science / Electrical power
Electrical power calculator
Calculate DC or resistive-circuit power, current, energy, and cost.
On this page
Power1,150W
Energy9.2kWh
Energy cost1.84
Calculator controls
How to calculate
Calculate DC or resistive-circuit power, current, energy, and cost.
power = voltage × current; energy = power × time
Worked example
Voltage (V): 230; Current (A): 5; Run time (hours): 8; Price per kWh: 0.2.
Power: 1,150 W; Energy: 9.2 kWh; Energy cost: 1.84 .
Assumptions and limits
For AC motors and reactive loads, power factor and efficiency matter. Verify circuit ratings and use a qualified electrician for installation decisions.
Results are rounded for display; calculations use unrounded values. Read our calculation methodology.
Understanding the result
Calculate DC or resistive-circuit power, current, energy, and cost. The result follows the displayed formula and keeps every adjustable assumption visible.
When this tool is useful
Use this tool to plan quantities or compare scenarios before making a purchase or technical decision.
Understanding your inputs
| Input | What to enter |
|---|---|
| Voltage (V) | Enter a number of at least 0 and no more than 1000000000000. |
| Current (A) | Enter a number of at least 0 and no more than 1000000000000. |
| Run time (hours) | Enter a number of at least 0 and no more than 1000000000000. |
| Price per kWh | Enter a number of at least 0 and no more than 1000000000000. |
Frequently asked questions
What can change the electrical power result?
For AC motors and reactive loads, power factor and efficiency matter. Verify circuit ratings and use a qualified electrician for installation decisions.
Should I round the inputs first?
No. Enter the best measurements available and round only the practical final quantity, such as full packs, boards, sheets, or components.