Power Calculator
Calculate electrical power using voltage and current: P = V × I
Color Bands
Resistance Value
Calculated Result
Interactive Circuit
Understanding Resistor Color Codes
Resistor values are indicated by colored bands that represent numbers and multipliers:
Color Values (1st-3rd Bands)
- ⚫ Black = 0
- 🟫 Brown = 1
- 🔴 Red = 2
- 🟧 Orange = 3
- 🟡 Yellow = 4
- 🟢 Green = 5
- 🔵 Blue = 6
- 🟣 Violet = 7
- ⚪ Gray = 8
- ⚪ White = 9
Multiplier (4th Band)
The fourth band is the multiplier:
- ⚫ Black: ×1 Ω
- 🟫 Brown: ×10 Ω
- 🔴 Red: ×100 Ω
- 🟧 Orange: ×1 kΩ
- 🟡 Yellow: ×10 kΩ
- 🟢 Green: ×100 kΩ
- 🔵 Blue: ×1 MΩ
- 🟣 Violet: ×10 MΩ
Tolerance (5th Band)
- 🟫 Brown: ±1%
- 🔴 Red: ±2%
- 🟢 Green: ±0.5%
- 🔵 Blue: ±0.25%
- 🟣 Violet: ±0.1%
- ⚪ Gray: ±0.05%
- 🟨 Gold: ±5%
- ⚫ Silver: ±10%
Understanding Electrical Power
Real-World Examples
Household Appliance
A 120V toaster drawing 10A of current consumes: P = 120V × 10A = 1200W of power
LED Light
A 12V LED strip using 2A of current consumes: P = 12V × 2A = 24W of power
Common Mistakes to Avoid
Confusing Energy and Power
Power (watts) is the rate of energy transfer, while energy (watt-hours) is power over time.
Ignoring Power Ratings
Always check component power ratings to prevent damage from excessive power.
Tips for Success
Safety Margin
Add 20% safety margin to calculated power requirements.
Check Efficiency
Consider power supply efficiency in your calculations.
Heat Management
Higher power means more heat - plan for cooling.
Energy Consumption
To calculate energy consumption, multiply power by time:
E = P × t
Energy (Wh) = Power (W) × Time (h)
Cost = E × Rate
Cost ($) = Energy (kWh) × Rate ($/kWh)