How to Calculate Electrical Power
What is Electrical Power?
Electrical power is the rate at which electrical energy is transferred or converted. The three equivalent power formulas (P = VI, P = I²R, P = V²/R) allow power to be calculated from any two of the three fundamental quantities (V, I, R). Power is measured in watts (W), where 1 watt = 1 joule per second.
Formula
- P
- watts × seconds) — watts × seconds)
- V
- voltage × current) — voltage × current)
- I
- voltage × current) — voltage × current)
Step-by-Step Guide
- 1P = V × I (power = voltage × current)
- 2P = I² × R (useful when voltage is unknown)
- 3P = V² / R (useful when current is unknown)
- 4Energy consumed: E = P × t (joules = watts × seconds)
- 5kWh (unit on electricity bills) = kilowatts × hours
Worked Examples
Frequently Asked Questions
What is Power Calc?
Electrical power is the rate at which electrical energy is transferred or converted. The three equivalent power formulas (P = VI, P = I²R, P = V²/R) allow power to be calculated from any two of the three fundamental quantities (V, I, R)
How accurate is the Power Calc calculator?
The calculator uses the standard published formula for power calc. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.
What units does the Power Calc calculator use?
This calculator works with inches, kilowatts, watts. You can enter values in the units shown — the calculator handles all conversions internally.
What formula does the Power Calc calculator use?
The core formula is: P = V × I (power = voltage × current). Each step in the calculation is shown so you can verify the result manually.
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