Power Consumption Calculator
Calculate electrical power, voltage, current, resistance, and energy consumption cost.
Find Power (P)
Find Voltage (V)
Find Current (I)
Find Resistance (R)
Energy & Cost
V
kV
A
mA
Ω
kΩ
Enter any two values (V, I, R) depending on selected formula.
Power (P)
0.00 W
Formula: P = V × I
Formula Used
P = V × I
Additional
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Equivalent
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Electrical Power Formulas
P = V × I
P = I² × R
P = V² / R
P: Power (watts, W)
V: Voltage (volts, V)
I: Current (amperes, A)
R: Resistance (ohms, Ω)
Energy: E (kWh) = P (kW) × t (h)
Cost: = E × rate ($/kWh)
People Also Ask
🤔 How do I calculate power consumption of an appliance?
Multiply voltage (V) by current (A) to get power in watts. For energy, multiply power (kW) by hours used.
🔍 What is the difference between kW and kWh?
kW is power (rate of consumption), kWh is energy (total consumed). 1 kW for 1 hour = 1 kWh.
⚡ How to calculate electricity cost?
Energy (kWh) × rate ($/kWh). Our calculator does it automatically.
📏 What is Ohm's law?
V = I × R. It relates voltage, current, and resistance. Combined with power formulas, you can derive many quantities.
🎯 Why do we use √ in some power formulas?
From P = V²/R, solving for V gives V = √(P×R). Similarly, from P = I²R, I = √(P/R).
🔥 Real-world applications?
Sizing wires, selecting circuit breakers, estimating electricity bills, designing power supplies.
Understanding Power Consumption
Electrical power is the rate at which electrical energy is converted to another form (heat, light, motion). It's measured in watts (W).
The basic formula is P = V × I. Using Ohm's law (V = I × R), we can also write:
- P = I² × R
- P = V² / R
For energy consumption, we multiply power by time: E (kWh) = P (kW) × t (h).
Typical Appliance Power Ratings
| Appliance | Typical Power (W) | Daily Use (h) | Est. Monthly Cost* |
|---|---|---|---|
| LED Bulb | 10 | 5 | $0.23 |
| Refrigerator | 150 | 24 | $16.20 |
| Laptop | 50 | 4 | $0.90 |
| Air Conditioner | 1500 | 8 | $54.00 |
| Electric Heater | 2000 | 3 | $27.00 |
*Assumes $0.15/kWh, 30 days.
Common Questions
How to convert watts to kilowatts?
Divide by 1000. 1000 W = 1 kW.
What is power factor in AC circuits?
For AC, real power P = V × I × cosφ. This calculator assumes DC or resistive AC (cosφ=1).