How to Use the Resistor Color Code Calculator
This calculator helps you determine the resistance value, tolerance, and temperature coefficient of color-coded resistors. The color bands are read from left to right, and each color represents a specific digit, multiplier, tolerance, or temperature coefficient.
We Support Following Resistor Types and Calculations:
- Three Band Resistor (2 digits, multiplier)
- Four Band Resistor (2 digits, multiplier, tolerance)
- Five Band Resistor (3 digits, multiplier, tolerance)
- Six Band Resistor (3 digits, multiplier, tolerance, temperature coefficient (PPM))
Steps to Calculate:
- Select the number of color bands on your resistor (3, 4, 5, or 6 bands)
- Click on the colored squares in the table to match your resistor's bands from left to right
- The resistance value will be calculated and displayed automatically
- Use "Show Advanced" to see minimum/maximum values and temperature coefficient
Band Configurations:
3-Band Resistors: Band 1 (1st digit) + Band 2 (2nd digit) + Band 3 (multiplier). Default tolerance is ±20%.
4-Band Resistors: Band 1 (1st digit) + Band 2 (2nd digit) + Band 3 (multiplier) + Band 4 (tolerance).
5-Band Resistors: Band 1 (1st digit) + Band 2 (2nd digit) + Band 3 (3rd digit) + Band 4 (multiplier) + Band 5 (tolerance).
6-Band Resistors: Same as 5-band, plus Band 6 for temperature coefficient of resistance (TCR).
Reading Direction:
Resistor bands are read from left to right. The tolerance band (gold or silver) is usually at the right end and may be slightly separated from other bands. If unsure of the reading direction, remember that gold and silver are never used for significant digits.
Color Code Standard:
This calculator follows the international standard IEC 60062:2016, which defines the color coding system for resistors and capacitors used worldwide.
Understanding Resistor Color Code Bands
1st Band (First Digit)
The first band on a resistor represents the first significant digit of the resistance value. Each color corresponds to a digit from 0 to 9.
2nd Band (Second Digit)
The second band represents the second significant digit. It works together with the first digit to form the base numeric value of resistance.
3rd Band (Third Digit, if applicable)
In 5-band and 6-band resistors, the third band represents the third significant digit, providing more precision.
Multiplier Band
The multiplier band determines by what factor you multiply the digits formed by the first bands. For example, if your digits are 47 and the multiplier band is red (×100), the resistor value is 4700 ohms (4.7kΩ).
Tolerance Band
The tolerance band indicates how accurately the resistor meets its stated resistance value. Common tolerances are ±1% (brown), ±5% (gold), and ±10% (silver).
Temperature Coefficient of Resistance (TCR - ppm/K)
The TCR band (in 6-band resistors) tells you how much the resistance changes with temperature variations. It is measured in parts per million per Kelvin (ppm/K). Lower values indicate better temperature stability.
What Resistor Exceptions Exist?
Although most resistors follow standard color coding, some specialized resistors don't match these conventions:
- Zero-Ohm Resistors: Single black band or marked "0". Used as jumpers in PCB layouts for automated assembly. Acts like a wire connection.
- Military Resistors: May have an additional band indicating failure rate or reliability level. Usually follows MIL-PRF-55182 standard.
- Precision Resistors: Often printed numerically because their tolerances are too tight for the standard color code to represent clearly.
- Surface-Mount (SMD) Resistors: Usually marked numerically rather than with colors due to size constraints.
- Wire-Wound and High-Power Resistors: Frequently labeled numerically since they handle higher power and temperatures, making color coding impractical.
These specialized resistors are essential for applications requiring higher accuracy, stability, or power dissipation beyond typical resistors.
How to Calculate Resistor Values Yourself (Without a Table)
You can easily remember or calculate resistor values manually using the mnemonic for colors: "Black (0), Brown (1), Red (2), Orange (3), Yellow (4), Green (5), Blue (6), Violet (7), Grey (8), White (9)."
Here’s how to do it:
- Identify Significant Digits: Match the colors of the first two or three bands to the corresponding numbers using the mnemonic above.
- Determine the Multiplier: Convert the color of the multiplier band to its numeric factor (e.g., Red is ×100, Orange ×1,000).
- Calculate Resistance: Multiply the significant digits by the multiplier.
- Tolerance: The tolerance band tells you how much variance to expect from the calculated value.
Example: Red (2), Violet (7), Orange (×1,000), and Gold (±5%) would mean 27 × 1,000 = 27,000Ω (27kΩ) with ±5% tolerance.
By understanding these basics, you can quickly decode resistor values even without reference tables, aiding both practical work and learning.