Resistor Color Code Calculator

This Resistor Color Code Calculator helps you determine the resistance value of a resistor based on its color bands. Here’s how to use it:

  1. Select Band Colors:
    • Use the dropdowns to choose the colors for Band 1, Band 2, Multiplier, and Tolerance.
    • Each color represents a specific digit, multiplier, or tolerance percentage.
  2. Calculate Resistance:
    • After selecting the bands, click the Calculate button.
  3. View Results:
    • The result will display the resistance value in ohms (Ω) along with the tolerance percentage (e.g., Resistance: 470Ω ±5%).

This tool is ideal for quickly decoding resistor values during electronics projects.

Resistor Color Coding Made Simple

Color coding is a handy way to show the resistance, tolerance, and sometimes the temperature rating of small resistors. It works because printing numbers on tiny resistors is tricky. You’ll also see color codes on parts like capacitors, inductors, and diodes.

Big resistors don’t need color codes since there’s enough space to print the values directly. For tiny surface-mounted resistors (SMDs), numbers and letters replace color codes. All of this follows a standard called IEC 60062:2016—basically, the official rulebook for these codes.

How to Read the Colors

Most resistors have three to six color bands. Each band tells you something: the resistance, tolerance, or temperature rating. The colors are read from left to right. But knowing where to start isn’t always obvious. Here’s a quick trick:

  • Look for a wider band or a gap between bands—that’s usually the tolerance band, and it’s on the right.
  • If there’s a gold or silver band, it’s always on the far-right side.

When in doubt, check the datasheet or use a multimeter to confirm the value.

Types of Color Bands

  • Three-band resistors:
    The first two colors are the resistance digits. The third is the multiplier. Tolerance is fixed at ±20%.
  • Four-band resistors (the most common):
    The first two colors are the digits. The third is the multiplier. The fourth is the tolerance.
  • Five-band resistors:
    The first three colors are the digits. The fourth is the multiplier. The fifth is the tolerance.
  • Six-band resistors:
    These are like five-band resistors but with one extra band for temperature rating (TCR).

What Tolerance Means

Tolerance tells you how close the actual resistance is to the printed value. For example, a 1 kΩ resistor with ±5% tolerance might actually measure anywhere from 950 Ω to 1.05 kΩ.

How to Calculate the Resistance

Here’s how to figure it out:

  1. Look at the first two (or three) color bands for the digits.
  2. Multiply those digits by the number from the multiplier band.
  3. Use the tolerance band to find the possible range of values.

Example:

Let’s say you have a resistor with these bands: Violet, Green, Yellow, and Gold.

  1. Violet (7) and Green (5) are the digits: 75.
  2. Yellow is the multiplier: ×10⁴ = 10,000.
    • Resistance = 75 × 10,000 = 750,000 Ω or 750 kΩ.
  3. Gold means ±5% tolerance.
    • Minimum = 750,000 – 5% = 712,500 Ω or 712.5 kΩ.
    • Maximum = 750,000 + 5% = 787,500 Ω or 787.5 kΩ.

Special Cases

  • Zero-ohm resistors: These are like tiny wires with one black band. They connect two points on a circuit board.
  • Military-grade resistors: These may have an extra band to show how reliable they are.
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