Resistor Color Code Calculator

To read a resistor color code, identify the number of color bands on the resistor. For a 4-band resistor: the first two bands represent digits, the third is the multiplier, and the fourth is the tolerance. For a 5-band resistor: the first three bands are digits, the fourth is the multiplier, the fifth is tolerance, and the optional sixth is TCR.

4-band resistors have two significant digits and are used for standard precision components. 5-band resistors have three significant digits, providing greater accuracy, and are used in precision applications. 5-band resistors also sometimes include a 6th band indicating the Temperature Coefficient of Resistance (TCR).

The tolerance band indicates the acceptable variation in the resistor's actual value from its nominal value. For example, a 100Ω resistor with ±5% tolerance (gold band) may have an actual resistance between 95Ω and 105Ω. Lower tolerance percentages mean higher precision.

TCR (Temperature Coefficient of Resistance) indicates how much the resistance changes with temperature, measured in parts per million per degree Celsius (ppm/°C). A lower TCR means the resistor's value stays more stable across temperature changes, which is important in precision circuits.

The gold band on a resistor indicates ±5% tolerance when used as the tolerance band. As a multiplier band, gold represents ×0.1 (divides by 10). Gold is one of the most common tolerance bands found on general-purpose resistors.

A silver band as the tolerance band means ±10% tolerance. As a multiplier band, silver represents ×0.01 (divides by 100). Silver tolerance resistors are less precise than gold (±5%) or colored band resistors.

Select whether your resistor has 4 or 5 bands using the buttons at the top. Then choose the color for each band from the dropdown menus. The calculator automatically computes the resistance value, tolerance, and acceptable range. You can also view the full color reference chart below the inputs.

For a 1kΩ resistor with ±5% tolerance (4-band): Brown (1), Black (0), Red (×100), Gold (±5%). The first two bands give 10, and multiplied by 100 gives 1000Ω = 1kΩ. Brown-Black-Red-Gold is one of the most frequently used color codes in electronics.

If no tolerance band is present (or a blank/body-color gap), the resistor has ±20% tolerance. These are older or very basic components. Modern resistors almost always include a gold or silver tolerance band for clearer specification.

This calculator is designed for through-hole resistors with color bands. SMD (Surface Mount Device) resistors use a numeric code printed directly on the component (e.g., '103' for 10kΩ) rather than color bands. For SMD resistors, you would use a separate SMD resistor code decoder.

All colors from black to white can be used as multiplier bands (representing ×1 to ×1,000,000,000). Additionally, gold (×0.1) and silver (×0.01) are used as multipliers for values below 10Ω. The most common multiplier bands in practice are red (×100), orange (×1k), and yellow (×10k).

Color-coded resistors have standard tolerance values. The most common tolerances are ±1% (brown), ±2% (red), ±5% (gold), and ±10% (silver). For high-precision applications, 5-band resistors with ±0.1% (violet) or ±0.05% (grey) tolerance are used. Always verify with a multimeter for critical circuits.