Resistor Color Code

Decode resistor color bands to resistance values or convert a resistance value to color bands. Supports 4-band, 5-band, and 6-band resistors.

How It Works

Reading Resistor Color Bands

Resistors use colored bands painted around their body to indicate resistance value, tolerance, and sometimes temperature coefficient. The bands are read from left to right, starting from the band closest to one end of the resistor.

Band Configurations

• 4-Band: 2 significant digits + multiplier + tolerance. Most common for general-purpose resistors (typically 5% or 10% tolerance).
• 5-Band: 3 significant digits + multiplier + tolerance. Used for precision resistors (typically 1% or 2% tolerance).
• 6-Band: Same as 5-band plus a temperature coefficient band. Used for high-precision applications where thermal stability matters.

Calculating Resistance

The significant digit bands form a number, which is then multiplied by the multiplier band value. For example, a 4-band resistor with Yellow (4), Violet (7), Red (×100), Gold (±5%) reads as: 47 × 100 = 4,700 Ω (4.7 kΩ) ±5%.

Tolerance

The tolerance band indicates how much the actual resistance may differ from the stated value. A 4.7 kΩ resistor with 5% tolerance has an actual value between 4,465 Ω and 4,935 Ω. Tighter tolerances (1%, 0.1%) are needed for precision circuits like filters and measurement equipment.

Temperature Coefficient

The 6th band on precision resistors indicates the temperature coefficient in ppm/°C (parts per million per degree Celsius). This tells you how much the resistance changes with temperature. Lower values indicate more stable resistors.