Resistor Color Code Calculator Formula

Understand the math behind the resistor color code calculator. Each variable explained with a worked example.

Use the Resistor Color Code Calculator

Formulas Used

Resistance

resistance = base_val * pow(10, multiplier_exp)

Resistance (k)

resistance_k = base_val * pow(10, multiplier_exp) / 1000

Variables

VariableDescriptionDefault
band1Band 1 Digit (0-9)4
band2Band 2 Digit (0-9)7
multiplier_expMultiplier (10^x)2
base_valDerived value= band1 * 10 + band2calculated

How It Works

Resistor Color Codes

4-Band System

  • Band 1: First digit
  • Band 2: Second digit
  • Band 3: Multiplier (10^x)
  • Band 4: Tolerance

    • Black=0, Brown=1, Red=2, Orange=3, Yellow=4, Green=5, Blue=6, Violet=7, Grey=8, White=9

    Worked Example

    Yellow(4), Violet(7), Red(x100).

    band1 = 4band2 = 7multiplier_exp = 2
    1. 01Base = 4 x 10 + 7 = 47
    2. 02Multiplier = 10^2 = 100
    3. 03Resistance = 47 x 100 = 4700 ohms = 4.7k

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