Resistor Calculator
Calculate resistor values by selecting color bands. Supports 4-band and 5-band resistors with instant resistance and tolerance output.
How to Read Resistor Color Codes
Resistors use colored bands to indicate their resistance value and tolerance. Reading them is easy once you know the pattern.
4-Band Resistors
- Band 1 & 2: The first two digits of the resistance value.
- Band 3 (Multiplier): The number of zeros to add (multiplication factor).
- Band 4 (Tolerance): The precision of the resistor (e.g., Gold = 5%).
5-Band Resistors
Used for higher precision resistors.
- Band 1, 2, & 3: The first three digits of the value.
- Band 4 (Multiplier): The multiplication factor.
- Band 5 (Tolerance): The precision.
Example
A 4-band resistor with colors Yellow, Violet, Red, Gold:
Yellow (4), Violet (7) → 47
Red (x100) → 47 × 100 = 4,700 Ω = 4.7 kΩ
Gold (±5%) → Tolerance is 5%.
? Frequently Asked Questions
Usually, the tolerance band (Gold/Silver) is spaced further apart from the others. Start reading from the opposite end. If in doubt, look for bands that can't be the first digit (like Gold/Silver/Black).
Tolerance indicates how much the actual resistance might vary from the stated value. A 100Ω resistor with 5% tolerance could measure anywhere between 95Ω and 105Ω.
5-band resistors provide an extra digit of precision (3 significant figures instead of 2). They are typically metal film resistors with tighter tolerances (1% or less) compared to standard carbon film resistors.