Calculate Electrical Power using Different Formulas
Enter any two values to calculate power and other parameters
Basic Power Formula
P = V × I
Power with Resistance
P = I² × R
Power with Voltage & Resistance
P = V² ÷ R
Mechanical Power
P = W ÷ t
| Unit | Symbol | Equivalent |
|---|---|---|
| Watt | W | 1 J/s |
| Kilowatt | kW | 1,000 W |
| Megawatt | MW | 1,000,000 W |
| Horsepower | hp | 745.7 W |
Power is the rate at which electrical energy is transferred by an electric circuit per unit time.
Our comprehensive Power Calculator helps students, engineers, and electricians calculate electrical power using multiple formulas and methods. Solve complex power problems, understand power factor, and analyze electrical systems with precision and accuracy.
Calculate power using P=VI, P=I²R, P=V²/R, and three-phase power formulas with automatic unit conversions.
Handle both DC power calculations and AC power with power factor, apparent power, and reactive power components.
Calculate motor power, heater wattage, circuit loading, and energy consumption for practical electrical work.
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P = V × I
Power = Voltage × Current
Most fundamental power formula
P = I² × R
Power = Current² × Resistance
Useful when resistance is known
P = V² ÷ R
Power = Voltage² ÷ Resistance
Useful when voltage and resistance are known
P = V × I × PF
Real Power = Voltage × Current × Power Factor
For single-phase AC systems
P = √3 × VL × IL × PF
Three-phase power formula
Line voltage and line current
S = V × I
Apparent Power = Voltage × Current
Vector sum of real and reactive power
Actual power consumed, measured in watts (W)
Does useful work like heating, lighting
Power stored and returned, measured in VAR
Magnetizes motors and transformers
Vector sum of real and reactive power, VA
Total power flowing in the circuit
Real power (P) is the actual power consumed and converted to useful work, measured in watts. Apparent power (S) is the vector sum of real power and reactive power, measured in volt-amperes. The ratio of real power to apparent power is the power factor, which indicates how effectively electrical power is being used.
For balanced three-phase systems, use the formula: P = √3 × VL × IL × PF, where VL is line-to-line voltage, IL is line current, and PF is power factor. For example, a 480V three-phase system drawing 50A at 0.85 power factor delivers: √3 × 480V × 50A × 0.85 = 35.3 kW of real power.
Power factor affects system efficiency and cost. Low power factor means higher current for the same real power, leading to increased energy losses, larger conductors, and potential utility penalties. Industrial facilities often use power factor correction capacitors to improve efficiency and reduce costs. Ideal power factor is 1.0, but typical values range from 0.7 to 0.95.
Always use properly rated circuit breakers or fuses for overload protection
Use correct wire gauge based on calculated current and NEC standards
Ensure proper grounding and bonding for safety and equipment protection
Never exceed rated capacities of electrical components and systems