How to Identify Band 1: Reading Resistors the Right Way
Which side do I start from?
Before using the calculator, ensure you are holding your resistor in the correct orientation. Reading a resistor from the wrong side will result in an incorrect value.
To read your resistor correctly, hold it so the band closest to the metal lead is on your left. Look for a wider gap near the end of the resistor; the band after that gap is the tolerance (last) band.
1. The Wide Gap Rule
Most resistors have a larger space between the multiplier band and the tolerance band. The grouped bands always go on the left.
2. The Gold/Silver Rule
If you see a Gold or Silver band, it is almost certainly the tolerance band. Place it on the right side of the resistor.
Why are there standard resistor color codes?
A Resistor Color Code is a system of colored bands used to identify the resistance value, tolerance, and temperature coefficient of a resistor. Since resistors are often too small to have numbers printed on them, manufacturers use this standardized color-coding system (defined by IEC 60062) to indicate their specifications.
Understanding how to read these codes is a fundamental skill for anyone working with electronics, from hobbyists using an Arduino to professional engineers designing complex PCBs. The color code allows you to determine the resistor's value in Ohms (Ω), how precise that value is (tolerance), and in some cases, how much the resistance changes with heat.
Resistor Color Code Chart
Use the chart below to manually decode resistor values. This table follows the standard IEC 60062 coding system used by engineers worldwide.
| Color | 1st Band | 2nd Band | Multiplier | Tolerance |
|---|---|---|---|---|
| Black | 0 | 0 | 1 Ω | - |
| Brown | 1 | 1 | 10 Ω | ± 1% |
| Red | 2 | 2 | 100 Ω | ± 2% |
| Orange | 3 | 3 | 1 kΩ | - |
| Yellow | 4 | 4 | 10 kΩ | - |
| Green | 5 | 5 | 100 kΩ | ± 0.5% |
| Blue | 6 | 6 | 1 MΩ | ± 0.25% |
| Violet | 7 | 7 | 10 MΩ | ± 0.1% |
| Grey | 8 | 8 | - | ± 0.05% |
| White | 9 | 9 | - | - |
| Gold | - | - | 0.1 Ω | ± 5% |
| Silver | - | - | 0.01 Ω | ± 10% |
How to Read a Resistor Color Code Chart
To read a resistor color code chart, start by identifying the number of bands on your resistor. Hold the resistor so that the band closest to an end is on your left; this is your first significant digit. For a standard 4-band resistor, the first two bands represent the primary digits, the third band is the multiplier (which indicates how many zeros to add), and the final band—usually spaced slightly apart—indicates the tolerance.
Precision 5-band and 6-band resistors include a third significant digit band before the multiplier to provide more accuracy. In a 6-band resistor, the final band specifies the Temperature Coefficient (TCR), which tells you how much the resistance value fluctuates with temperature changes. By matching each colored ring to its corresponding numerical value on the chart, you can instantly determine the total resistance and its operational limits.
How to Calculate Resistance (The Formula)
Calculating resistance from color bands involves decoding the significant digits and the multiplier. You can think of it as a practical application of the values found in an Ohm's law formula triangle context.
4-Band Resistor Formula
The 4-band code is the most common. The first two bands represent the first two digits of the resistance value. The third band is the multiplier (power of 10). The fourth band is the tolerance.
R = (Band1 × 10 + Band2) × 10Band3
Example: Red (2), Red (2), Orange (1k), Gold (5%) = 22 × 1,000 = 22,000Ω or 22kΩ ±5%.
5-Band Resistor Formula
Used for higher precision resistors (1% or better). The first three bands are significant digits.
R = (Band1 × 100 + Band2 × 10 + Band3) × 10Band4
6-Band Resistor Formula
Identical to the 5-band system but adds a sixth band for the Temperature Coefficient (PPM/K). This tells you how much the resistance drifts as the component warms up—crucial for sensitive analog circuits.
Practical Applications
Resistors are ubiquitous in electronics. Here are some common real-world applications where calculating the correct resistance is critical:
- LED Current Limiting: Using an LED series resistor calculator principle, you must choose the right resistor to prevent an LED from burning out. For example, connecting a 220Ω resistor in series with a red LED on a 5V supply.
- Voltage Division: Creating a reference voltage for microcontrollers using the voltage divider rule.
- Pull-up/Pull-down Resistors: Ensuring digital input pins on chips like the ATmega328P have a defined state when no switch is pressed.
- Timing Circuits: Working with a capacitor to create precise time delays in 555 timer circuits.
Commonly used resistors colour code
Brown, Black, Brown, Gold
Red, Red, Brown, Gold
Orange, Orange, Brown, Gold
Yellow, Violet, Brown, Gold
Brown, Black, Red, Gold
Red, Red, Red, Gold
Yellow, Violet, Red, Gold
Brown, Black, Orange, Gold
Brown, Black, Yellow, Gold
Brown, Black, Green, Gold
SMD Resistor Codes: How to Read Numbers
Unlike through-hole resistors, SMD components use numbers. A 3-digit code like 103 means 10 followed by 3 zeros (10kΩ).
Frequently Asked Questions (FAQ)
Q: How do I read a 5-band resistor color code?
To read a 5-band precision resistor, read the first three bands as significant digits (e.g., Brown-Black-Black = 100). The fourth band is the multiplier (e.g., Red = x100). The fifth band is the tolerance (e.g., Brown = 1%). So, 1-0-0 x 100 = 10,000Ω or 10kΩ.
[Image of 5-band resistor color code diagram]Q.Can This Tool be used to calculate resistance of 5 or 6 stripe resistor?
Yes this tool can be used to calculate resistance of 5 or 6 stripe resistor. A 6-band resistor is an extension of the 5-band precision resistor. The bands are broken down as follows:
- First Three Bands: Significant digits (e.g., Brown, Black, Black = 1, 0, 0).
- Fourth Band: The Multiplier (the power of 10 to multiply the digits by).
- Fifth Band: The Tolerance (the allowed margin of error, usually ±1% or ±0.5%).
- Sixth Band: The Temperature Coefficient (TCR), which indicates how much the resistance changes as the component heats up.
Q: Why do I need a current-limiting resistor for an LED?
LEDs are non-ohmic devices that draw excessive current if connected directly to a voltage source. A resistor is placed in series to limit this current to a safe level (typically 20mA), preventing the LED from overheating and burning out immediately. To find the correct value, subtract the LED's forward voltage from your source voltage and divide by the desired current (R = V/I).
Q: What is the difference between series and parallel resistors?
In a series circuit, components are connected end-to-end, so the same current flows through all of them. The total resistance is found by adding all individual resistance values together.
In a parallel circuit, components are connected across the same voltage points, splitting the current between paths. Resistors decrease in total resistance when in parallel.
