Electrical Power Calculator
Calculate power, current, voltage, and resistance using electrical formulas
Standard US: 120V, EU: 230V
Common appliances:
Formulas Used
• P = V × I (Voltage × Current)
• P = V² / R (Voltage² ÷ Resistance)
• P = I² × R (Current² × Resistance)
• I = P / V (Power ÷ Voltage)
• I = V / R (Voltage ÷ Resistance)
• V = P / I (Power ÷ Current)
• V = I × R (Current × Resistance)
• R = V / I (Voltage ÷ Current)
• R = V² / P (Voltage² ÷ Power)
• R = P / I² (Power ÷ Current²)
= kW
Energy Consumption Estimate
| Per Hour | kWh |
| Per Day (8 hours) | kWh |
| Per Month (30 days × 8 hrs) | kWh |
| Est. Monthly Cost (@$0.12/kWh) | $ |
📐 Ohm's Law Triangle
Volts
Amps
Ohms
V = I × R
I = V ÷ R
R = V ÷ I
P = V × I
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About Electrical Power Calculator
What is an Electrical Power Calculator?
An electrical power calculator helps you determine the relationship between power (watts), current (amps), voltage (volts), and resistance (ohms) in electrical circuits. These calculations are fundamental to electrical engineering, home wiring, and understanding energy consumption.
How to Use This Calculator
- Select Calculation Mode: Choose what you want to calculate (Power, Current, Voltage, or Resistance)
- Enter Known Values: Input the values you already know
- Get Instant Results: See your calculated value with related information
Key Electrical Formulas
Ohm's Law
- V = I × R (Voltage = Current × Resistance)
- I = V / R (Current = Voltage / Resistance)
- R = V / I (Resistance = Voltage / Current)
Power Equations
- P = V × I (Power = Voltage × Current)
- P = I² × R (Power = Current² × Resistance)
- P = V² / R (Power = Voltage² / Resistance)
Understanding Electrical Units
| Unit | Symbol | Measures | Description |
|---|---|---|---|
| Watt | W | Power | Rate of energy transfer |
| Ampere | A | Current | Flow of electric charge |
| Volt | V | Voltage | Electrical potential difference |
| Ohm | Ω | Resistance | Opposition to current flow |
Common Power Ratings
| Appliance | Typical Power |
|---|---|
| LED Light Bulb | 7-15W |
| Incandescent Bulb | 40-100W |
| Laptop | 30-90W |
| Desktop PC | 200-500W |
| Microwave | 600-1200W |
| Hair Dryer | 1000-1875W |
| Electric Heater | 1000-1500W |
| Air Conditioner | 1000-5000W |
| Electric Stove | 2000-5000W |
Practical Applications
Home Electrical Planning
- Calculate circuit capacity requirements
- Determine if a circuit can handle additional loads
- Size breakers and wiring properly
Energy Cost Estimation
- Understand energy consumption in watts
- Calculate electricity costs based on usage
- Compare efficiency of different appliances
Electronics and DIY Projects
- Select appropriate resistors
- Design LED circuits
- Calculate battery requirements
Safety Considerations
Warning: Working with electricity can be dangerous. Always turn off power before working on electrical systems and consult a licensed electrician for major electrical work.
Important Safety Tips
- Never exceed rated amperage for wires or circuits
- Use proper gauge wire for the current load
- Ensure adequate ventilation for heat-generating devices
- Install proper overcurrent protection
Frequently Asked Questions
What's the difference between AC and DC power?
AC (Alternating Current) oscillates direction periodically, while DC (Direct Current) flows in one direction. This calculator works with both, but AC power calculations in complex systems may require additional considerations like power factor.
How do I calculate electrical cost?
Multiply power (kW) × time (hours) × rate ($/kWh). For example: 1000W × 8 hours × $0.12/kWh = $0.96.
What is power factor?
Power factor is the ratio of real power to apparent power in AC circuits. For simple resistive loads, power factor is 1. For inductive or capacitive loads, it can be less than 1.
How do kilowatts relate to watts?
1 kilowatt (kW) = 1,000 watts (W). Energy bills often use kilowatt-hours (kWh) which is power consumption over time.
Common Voltage Standards
🇺🇸 United States
120V / 60Hz (residential)
240V / 60Hz (appliances)
🇪🇺 Europe
230V / 50Hz (residential)
400V / 50Hz (industrial)
🇬🇧 United Kingdom
230V / 50Hz (residential)
🇦🇺 Australia
230V / 50Hz (residential)
⚠️ Safety Warning: Working with electricity can be extremely dangerous. Always turn off power before working on electrical systems and consult a licensed electrician for any electrical work.