Código de Colores de Resistencias

The resistor color code is an international standard established by IEC 60062 and EIA-RS-279 that uses painted colored stripes around axial lead resistors to indicate their resistance value (in ohms Ω), tolerance rating, and in precision 6-band components, their temperature coefficient (TCR in ppm/K).

Because through-hole resistors are tiny cylindrical components that rotate freely when inserted into a printed circuit board (PCB), printed alphanumeric text would often end up face down or obscured. Painted colored rings encircle the entire 360-degree circumference of the resistor body, ensuring the component value is always readable from any angle without needing an ohmmeter.

To calculate a resistor's value from its color bands, follow this 4-step sequence:

1. Identify Band Count: Check if you have a standard 4-band resistor (2 digits) or a precision 5-band / 6-band resistor (3 digits).
2. Read Significant Digits: Note the digit values from the bands closest to the left lead (e.g. Yellow = 4, Violet = 7 → "47").
3. Apply Multiplier: Look up the multiplier band (Band 3 on 4-band, Band 4 on 5/6-band) and multiply: e.g. Red is ×100 (×10²), giving 47 × 100 = 4,700 Ω (4.7 kΩ).
4. Verify Tolerance: Read the final tolerance band on the right (Gold = ±5%, Silver = ±10%, Brown = ±1%) to know the component's guaranteed resistance range.

Example: Yellow (4) – Violet (7) – Red (×100) – Gold (±5%) = 4.7 kΩ ±5% (operational range: 4,465 Ω to 4,935 Ω).

Calculating resistor color codes uses the mathematical formula: Resistance = [Significant Digits] × Multiplier ± Tolerance%.

• 4-Band Resistors: Value = (Band 1 × 10 + Band 2) × 10^{Band 3} Ω.
• 5-Band Resistors: Value = (Band 1 × 100 + Band 2 × 10 + Band 3) × 10^{Band 4} Ω.

Reverse Calculation (Ohms to Colors): Take the first two or three significant figures as your digit colors, count the remaining zeros to select the multiplier stripe, and add your tolerance band. For example, 10,000 Ω (10k) breaks down into digits '1' (Brown) and '0' (Black), with 3 remaining zeros (Orange = 10³), plus Gold (±5%).

To read a resistor color code correctly, orient the component and read the stripes from left to right:

1. Locate the Tolerance Band (Far Right): Look for the metallic Gold (±5%) or Silver (±10%) band. It is positioned at the far right and separated from the preceding bands by a visibly wider gap.
2. Read from Left to Right:
   • Band 1: First significant digit.
   • Band 2: Second significant digit.
   • Band 3: Third digit (for 5/6-band precision) OR Multiplier (for 4-band).
   • Band 4: Multiplier (for 5/6-band) OR Tolerance (for 4-band).
   • Band 5: Tolerance rating (for 5/6-band).
   • Band 6 (if present): Temperature Coefficient of Resistance in ppm/K.

Pro Tip: Gold and Silver never appear as the first significant digit, so if you see Gold or Silver on one side, that is definitely the end band.

To calculate resistors by color, map each band color to its standard numeric value:

Multipliers: Silver = ×0.01, Gold = ×0.1, Black = ×1, Brown = ×10, Red = ×100, Orange = ×1k, Yellow = ×10k, Green = ×100k, Blue = ×1M. Multiply the concatenated digits by the multiplier value to calculate total ohms.

Resistor formulas cover color decoding, Ohm's law, power dissipation, and series/parallel circuits:

• Color Code Formula (4-Band): R = (D1 × 10 + D2) × 10M Ω
• Color Code Formula (5-Band): R = (D1 × 100 + D2 × 10 + D3) × 10M Ω
• Ohm's Law: R = V / I (Resistance in Ω = Voltage in Volts ÷ Current in Amperes).
• Power Dissipation: P = V × I = I² × R = V² / R (wattage rating required, e.g., 1/4W, 1/2W).
• Series Network: Rtotal = R1 + R2 + ... + Rn
• Parallel Network: 1 / Rtotal = 1 / R1 + 1 / R2 + ... + 1 / Rn (or Rtotal = (R1 × R2) / (R1 + R2) for two resistors).

The universally accepted method to memorize the color sequence (Black, Brown, Red, Orange, Yellow, Green, Blue, Violet, Gray, White) is through a mnemonic acronym:

• Modern Clean Mnemonic: "Better Be Right Or Your Great Big Venture Goes Wrong"
• Classic Mnemonic: "Bad Boys Race Our Young Girls But Violet Generally Wins"

A 1 ohm (1 Ω) resistor is coded as:

• 4-Band Resistor (±5%): Brown – Black – Gold – Gold
  Brown (1) × 10 + Black (0) = 10. Multiplier Gold (×0.1) gives 10 × 0.1 = 1 Ω, with Gold tolerance (±5%).
• 5-Band Resistor (±1% Precision): Brown – Black – Black – Silver – Brown
  Brown (1), Black (0), Black (0) = 100. Multiplier Silver (×0.01) gives 100 × 0.01 = 1 Ω, with Brown tolerance (±1%).

Notice: For values under 10 Ω, Gold acts as a fractional multiplier (×0.1) and Silver acts as (×0.01).

The color code for a 22 Ω (22 ohm) resistor is:

• 4-Band Resistor (±5%): Red – Red – Black – Gold
  Red (2), Red (2), Multiplier Black (×1 Ω). Value: 22 × 1 = 22 Ω, with Gold tolerance (±5%).
• 5-Band Resistor (±1% Precision): Red – Red – Black – Gold – Brown
  Red (2), Red (2), Black (0), Multiplier Gold (×0.1). Value: 220 × 0.1 = 22 Ω, with Brown tolerance (±1%).

Common Applications: 22 Ω resistors are widely used in USB 2.0 D+ and D- data line series termination for characteristic impedance matching, in audio output damping, and low-side current sensing.

A 100 ohm (100 Ω) resistor is color coded as:

• 4-Band Resistor (±5%): Brown – Black – Brown – Gold
  Brown (1), Black (0), Multiplier Brown (×10). Value: 10 × 10 = 100 Ω, with Gold tolerance (±5%).
• 5-Band Resistor (±1% Precision): Brown – Black – Black – Black – Brown
  Brown (1), Black (0), Black (0), Multiplier Black (×1). Value: 100 × 1 = 100 Ω, with Brown tolerance (±1%).

Common Applications: 100 Ω resistors are found in nearly every electronic design for BJT transistor base current protection, microcontroller GPIO pin current buffering, and differential signal bus termination.

A 750 ohm (750 Ω) resistor is color coded as:

• 4-Band Resistor (±5%): Violet – Green – Brown – Gold
  Violet (7), Green (5), Multiplier Brown (×10). Value: 75 × 10 = 750 Ω, with Gold tolerance (±5%).
• 5-Band Resistor (±1% Precision): Violet – Green – Black – Black – Brown
  Violet (7), Green (5), Black (0), Multiplier Black (×1). Value: 750 × 1 = 750 Ω, with Brown tolerance (±1%).

Common Applications: 750 Ω is a standard E24 preferred value frequently chosen in video RF amplification stages (10× multiplier of 75 Ω video coax line), audio preamplifiers, and LED drivers on higher DC supply rails (9V–12V).

Here are the exact color codes for 1k Ω and 2k Ω resistors:

• 1k Ohm Resistor (1,000 Ω or 1 kΩ):
  4-Band (±5%): Brown – Black – Red – Gold (1, 0, ×100 = 1,000 Ω).
  5-Band (±1%): Brown – Black – Black – Brown – Brown (1, 0, 0, ×10 = 1,000 Ω).
• 2k Ohm Resistor (2,000 Ω or 2 kΩ):
  4-Band (±5%): Red – Black – Red – Gold (2, 0, ×100 = 2,000 Ω).
  5-Band (±1%): Red – Black – Black – Brown – Brown (2, 0, 0, ×10 = 2,000 Ω).

Key Comparison: Both 1k and 2k 4-band resistors share the exact same Black 2nd band and Red multiplier (×100). The sole difference is the 1st digit stripe: Brown (1) for 1k Ω vs. Red (2) for 2k Ω.

To determine the reading direction:

• Check for Gold or Silver: Gold and Silver are never significant first digits in IEC standards; they are tolerance or fractional multiplier bands. If you see Gold or Silver on an end, that band belongs on the far right.
• Look for Band Spacing: Manufacturers leave a noticeably wider gap between the multiplier stripe and the tolerance stripe. The tightly grouped bands belong on the left.
• Proximity to Lead: The first significant digit band is usually printed closer to the metal lead wire edge than the tolerance band.

The primary differences lie in precision and significant figures:

• 4-Band Resistor: Uses 2 significant digits, 1 decimal multiplier, and 1 tolerance band (typically ±5% Gold or ±10% Silver). Common in standard carbon film resistors.
• 5-Band Resistor: Uses 3 significant digits, 1 decimal multiplier, and 1 tolerance band (typically ±1% Brown or ±0.5% Green). Designed for metal film precision circuits where values like 47.5 kΩ or 10.2 kΩ require 3 digits of resolution.

The 6th band specifies the Temperature Coefficient of Resistance (TCR) expressed in parts per million per Kelvin (ppm/K). It indicates how much the component's resistance will drift when ambient temperature changes. For instance, Brown is 100 ppm/K, Red is 50 ppm/K, Orange is 15 ppm/K, and Yellow is 25 ppm/K. Lower ppm/K values signify superior thermal stability in aerospace, medical instrumentation, and precision analog audio gear.

Standard E-series are logarithmic preferred value sequences defined by IEC 60063 to ensure manufacturing tolerances cover resistance decades without wasteful overlaps:

• E12 (10% Tolerance): 12 values per decade (10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82).
• E24 (5% Tolerance): 24 values per decade (adds intermediate steps like 20, 24, 30, 36, 43, 51, 62, 75, 91).
• E96 (1% Tolerance): 96 precision values per decade (used for 1% metal film resistors).