Resistor Color Code

How do resistor color codes work?

Resistor color codes are a standardized marking system defined by IEC 60062 that encodes resistance value, tolerance, and reliability information as colored bands painted on axial-lead resistors. Each color represents a digit (0–9), a multiplier (10^0 to 10^9), or a tolerance percentage.

Four-band resistors use two significant digits, a multiplier, and a tolerance band. Five-band resistors add a third significant digit for greater precision (1% or better). Six-band resistors include a temperature coefficient band, critical for precision circuits where resistance drift must be controlled.

The color code system enables quick visual identification without measurement instruments. Reading starts from the band closest to one lead. The tolerance band (gold = ±5%, silver = ±10%, brown = ±1%) is typically spaced slightly farther from the other bands.

Formula: R = (D1 × 10 + D2) × 10^M (4-band) R = (D1 × 100 + D2 × 10 + D3) × 10^M (5/6-band) where D = digit value, M = multiplier exponent

Example Calculation

A 4-band resistor with Brown-Black-Orange-Gold bands: D1=1, D2=0, Multiplier=10^3, Tolerance=±5%. Resistance = (1×10 + 0) × 1000 = 10,000 Ω = 10 kΩ ±5% (range: 9.5 kΩ to 10.5 kΩ).

When to Use This Calculator

• Identifying the value of a through-hole resistor during circuit debugging or repair when the color bands are faded or ambiguous
• Verifying resistor values before soldering to confirm the correct component was picked from inventory
• Encoding a desired resistance value into color bands when creating schematic documentation or teaching materials
• Cross-referencing color codes with measured resistance to determine if a resistor has drifted out of tolerance

Common Mistakes to Avoid

• Reading the color bands from the wrong end — the tolerance band (gold or silver) is always on the opposite end from the first significant digit; if in doubt, measure with a multimeter
• Confusing orange (3) with red (2) or yellow (4) under poor lighting conditions — use a magnifier and good illumination for reliable identification
• Assuming all 5-band resistors are 1% tolerance — while most are, some 5-band resistors use the extra digit for wider tolerance values; always check the tolerance band color
• Forgetting that the color code system does not apply to SMD resistors — surface-mount resistors use a 3 or 4-digit numeric code printed on the body

How to Interpret Results

• The decoded resistance combines the significant-figure digits with the multiplier band — confirm it matches the value you expect before fitting the part.
• The tolerance band defines the guaranteed range: a 4.7 kΩ ±5% resistor may measure anywhere from 4.465 kΩ to 4.935 kΩ and still be in spec.
• 5-band and 6-band parts add a third significant figure (and a temperature-coefficient band on 6-band), giving tighter precision than 4-band resistors.
• Gold and silver in the multiplier position mean ×0.1 and ×0.01 (for sub-10 Ω values) — do not confuse them with the same colors used for tolerance.

Related Standards & References

• IEC 60062 — Marking codes for resistors and capacitors, defining the standard color code system
• IEC 60063 — Preferred number series for resistors and capacitors (E6, E12, E24, E48, E96, E192 series)

Frequently Asked Questions

How do I determine which end to start reading from on a resistor?

Start reading from the band closest to one end of the resistor body. The tolerance band (gold, silver, or a wider gap) is always on the opposite end. If ambiguous, the first band is never gold or silver—those are only used for tolerance or multiplier bands.

What is the difference between 4-band and 5-band resistors?

Four-band resistors have two significant digits and are typically ±5% or ±10% tolerance. Five-band resistors have three significant digits, providing higher precision (±1% or ±0.5%). Five-band types are standard in modern electronics where tighter tolerances are required for analog and precision circuits.

What does the 6th band on a resistor indicate?

The 6th band indicates the temperature coefficient of resistance (TCR), measured in ppm/°C. Brown = 100 ppm/°C, red = 50, orange = 15, yellow = 25, blue = 10, violet = 5. Low TCR is critical for precision circuits where resistance must remain stable across operating temperatures, such as voltage references and instrumentation amplifiers.