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Resistor Color Code Calculator Overview
The Resistor Color Code Calculator helps identify the resistance value, tolerance, and temperature coefficient of axial leaded resistors from their color bands. It supports common 4-band, 5-band, and 6-band resistor markings, so it can be used for quick part identification, repair work, circuit prototyping, and checking values before soldering a resistor into a board.
Color bands are used because many resistors are too small for printed text. The first bands give the significant digits, the next band gives the multiplier, and the tolerance band shows how far the actual resistance may vary from the nominal value. On a 6-band resistor, the final band usually indicates the temperature coefficient in ppm/K.
The standard resistor color code chart.
How to Use the Resistor Color Code Calculator
Count the color bands on the resistor body: 4, 5, or 6 bands are the most common.
Find the tolerance band first. It is often separated by a wider gap and may be gold, silver, brown, red, green, blue, or violet.
Read the resistor from the opposite end, starting with the significant digit bands.
Select each band color in the calculator. The tool returns the resistance value in Ω, kΩ, or MΩ, along with the tolerance.
For a 6-band resistor, also select the temperature coefficient band if it is present.
If the band spacing is unclear, compare the result with nearby standard resistor values. A value such as 10 kΩ, 4.7 kΩ, 220 Ω, or 1 MΩ is usually more likely than an unusual value on a general-purpose resistor.
A video guide from the original article is available here: How to read a resistor color code chart.
4-Band, 5-Band, and 6-Band Resistors
| Resistor Type | Band Roles | Typical Use |
|---|---|---|
| 4-band resistor | 2 significant digits, multiplier, tolerance | General-purpose resistors, often 5% or 10% tolerance |
| 5-band resistor | 3 significant digits, multiplier, tolerance | Precision resistors where one extra digit is needed |
| 6-band resistor | 3 significant digits, multiplier, tolerance, temperature coefficient | Precision and temperature-sensitive designs |
Resistor Color Code Table
| Color | Digit | Multiplier | Common Tolerance | Temperature Coefficient |
|---|---|---|---|---|
| Black | 0 | ×1 | 250 ppm/K | |
| Brown | 1 | ×10 | ±1% | 100 ppm/K |
| Red | 2 | ×100 | ±2% | 50 ppm/K |
| Orange | 3 | ×1 kΩ | 15 ppm/K | |
| Yellow | 4 | ×10 kΩ | 25 ppm/K | |
| Green | 5 | ×100 kΩ | ±0.5% | 20 ppm/K |
| Blue | 6 | ×1 MΩ | ±0.25% | 10 ppm/K |
| Violet | 7 | ×10 MΩ | ±0.1% | 5 ppm/K |
| Gray | 8 | ×100 MΩ | ±0.05% | 1 ppm/K |
| White | 9 | ×1 GΩ | ||
| Gold | ×0.1 | ±5% | ||
| Silver | ×0.01 | ±10% | ||
| No band | ±20% |
Some precision resistor series may use additional tolerance or temperature-coefficient markings. Always check the manufacturer datasheet when the resistor is part of a safety-critical, high-voltage, high-power, or precision measurement design.
4-Band Resistor Formula
A 4-band resistor is read as:
Resistance = (first digit second digit) × multiplier
For example, brown-black-orange-gold is 10 × 1000 Ω = 10000 Ω, or 10 kΩ ±5%.
5-Band Resistor Formula
A 5-band resistor adds a third significant digit:
Resistance = (first digit second digit third digit) × multiplier
For example, brown-black-black-red-brown is 100 × 100 Ω = 10000 Ω, or 10 kΩ ±1%.
6-Band Resistor Formula
A 6-band resistor is read like a 5-band resistor, but the sixth band gives the temperature coefficient. This value describes how much the resistor value changes with temperature.
For example, brown-black-black-red-brown-red is 10 kΩ ±1%, 50 ppm/K.
Examples: 10 kΩ and 100 Ω Resistor Color Codes
| Target Value | 4-Band Example | 5-Band Example | Meaning |
|---|---|---|---|
| 100 Ω | Brown - Black - Brown - Gold | Brown - Black - Black - Black - Brown | 100 Ω, with tolerance set by the final band |
| 220 Ω | Red - Red - Brown - Gold | Red - Red - Black - Black - Brown | 220 Ω, common in LED and signal circuits |
| 1 kΩ | Brown - Black - Red - Gold | Brown - Black - Black - Brown - Brown | 1000 Ω, or 1 kΩ |
| 4.7 kΩ | Yellow - Violet - Red - Gold | Yellow - Violet - Black - Brown - Brown | 4700 Ω, or 4.7 kΩ |
| 10 kΩ | Brown - Black - Orange - Gold | Brown - Black - Black - Red - Brown | 10000 Ω, or 10 kΩ |
| 1 MΩ | Brown - Black - Green - Gold | Brown - Black - Black - Yellow - Brown | 1000000 Ω, or 1 MΩ |
100 Ω resistor color code for a 4-band resistor.
How to Read Band Direction
The tolerance band is often placed slightly farther away from the other bands, making it a useful clue for orientation. On many 4-band resistors, gold or silver appears at the tolerance end. Start reading from the opposite side.
If the resistor has a brown or red tolerance band and both directions look plausible, calculate both possible values and compare them with standard resistor values. The value that belongs to a common E-series and matches the circuit context is usually the intended reading.
Resistor Color Bands by Type
Three-band resistors omit the tolerance band, so their tolerance is commonly treated as ±20%. Four-band resistors are common in everyday electronics. Five-band and six-band resistors are often used where tighter tolerance or better temperature stability is required.
What Is a Resistor?
A resistor is a passive electronic component that limits current, divides voltage, sets bias points, terminates signals, or converts electrical energy into heat. Fixed resistors have a nominal resistance value, while variable resistors such as potentiometers allow the resistance to be adjusted.
The rated value printed or marked on a resistor is not always the exact measured value. The actual value depends on tolerance, temperature, aging, and operating conditions. In precision circuits, the tolerance and temperature coefficient can matter as much as the nominal resistance.
Tolerance and Resistance Range
Tolerance tells you the expected variation around the nominal resistance value. For example, a 10 kΩ resistor with ±5% tolerance may measure from 9.5 kΩ to 10.5 kΩ under specified conditions.
| Nominal Value | Tolerance | Minimum Value | Maximum Value |
|---|---|---|---|
| 100 Ω | ±5% | 95 Ω | 105 Ω |
| 1 kΩ | ±1% | 990 Ω | 1010 Ω |
| 10 kΩ | ±0.1% | 9990 Ω | 10010 Ω |
| 1 MΩ | ±10% | 900 kΩ | 1.1 MΩ |
Standard Resistor Values and E-Series
Standard resistor values are organized into E-series such as E3, E6, E12, E24, E48, E96, and E192. Each series divides a decade into a fixed number of preferred values. Lower-count series are common for general designs, while higher-count series are used for closer tolerance and precision work.
| Series | Typical Tolerance Association | Values Per Decade | Typical Use |
|---|---|---|---|
| E3 | Wide tolerance | 3 | Non-critical pull-up, pull-down, and rough current limiting |
| E6 | 20% | 6 | General non-precision designs |
| E12 | 10% | 12 | Common analog and digital circuits |
| E24 | 5% | 24 | General-purpose through-hole and film resistors |
| E48 | 2% | 48 | Closer tolerance designs |
| E96 | 1% | 96 | Precision analog, filters, and measurement circuits |
| E192 | 0.5%, 0.25%, 0.1%, and tighter | 192 | High-precision applications |
Common Reading Mistakes
| Mistake | Why It Matters | How to Avoid It |
|---|---|---|
| Reading from the tolerance end | The digits and multiplier will be reversed, giving a wrong value. | Look for the wider gap or the gold/silver tolerance band first. |
| Confusing red, orange, brown, or gold bands | A small color difference can change the value by a factor of 10 or more. | Use good lighting and compare with nearby known resistors if possible. |
| Ignoring tolerance | A resistor may be in spec even if it does not measure exactly at the nominal value. | Calculate the allowed minimum and maximum resistance range. |
| Measuring in-circuit | Parallel circuit paths can make a resistor appear lower than its true value. | Lift one lead or remove the part when an accurate measurement is required. |
| Using color code for damaged parts | Heat, age, or coating damage can discolor bands. | Confirm with a multimeter and check the circuit schematic. |
Applications
Resistor color code reading is useful when repairing older equipment, identifying loose components, checking bill-of-material values, learning basic electronics, and confirming whether a resistor matches a schematic. It is especially helpful for axial through-hole resistors where the color bands are still the main marking method.
For surface-mount resistors, use an SMD Resistor Code Calculator instead, because SMD parts usually use printed numeric or alphanumeric codes rather than color bands.
FAQ
What does a gold band mean on a resistor?
A gold band is commonly used as a multiplier of ×0.1 or as a tolerance band of ±5%, depending on its position.
What does a silver band mean on a resistor?
A silver band is commonly used as a multiplier of ×0.01 or as a tolerance band of ±10%, depending on its position.
Why do some resistors have five bands?
Five-band resistors use three significant digits instead of two, which allows more precise nominal resistance values.
What is ppm/K on a resistor?
ppm/K means parts per million per kelvin. It describes the expected change in resistance for each 1 K temperature change.
Can I rely only on the color code?
The color code is a fast identification method, but it should be confirmed with a multimeter when the resistor is critical, old, overheated, or difficult to read.
