Tool to compute resistor color code. Electronic components, such as resistors, have their values designated by a color code and standardized.
Resistors' Color Code - dCode
Tag(s) : Electronics
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Resistors' Color Code
3-Band Resistor Calculator
4 band resistor calculator
5 band resistor calculator
6 band resistor calculator
Answers to Questions (FAQ)
What is a resistor? (Definition)
A resistor is an electrical/electronic component noted R that opposes the flow of current. The unit of measurement of a resistance is the ohm symbolized by: Ω.
How to calculate the value of a resistor?
To know the value of a resistance, use an ohm-meter here (affiliate link) or read the color code on the resistor.
The International Norm CEI 60757 (1983) define a color code to write the value of a resistor (but also capacitor coding, and some other electronic component).
Colors are associated to digits:
Example:
| 0 | Black |
| 1 | Brown |
| 2 | Red |
| 3 | Orange |
| 4 | Yellow |
| 5 | Green |
| 6 | Blue |
| 7 | Violet |
| 8 | Grey |
| 9 | White |
| -1 | Gold |
| -2 | Silver |
The more often, a resistor has 4 bands:
The two first band (or the three first) indicate a digit each (a digit correspond to a color)
The next band (third or fourth) indicates a multiplication factor (more exactly a power of 10) to the number formed by the two first digits.
The last one (fourth, sometimes fifth) indicates the tolerance or precision of the calculated value. When this band is absent, it means the largest tolerance: 20%.
Sometimes an additional band is coded for precise resistor, it indicates a coefficient of temperature (in ppm/Kelvin or ppm/°C)
Example: A resistor Yellow,Orange,Red, digits are: 4,3,2. The first 2 digits make the number 43. The 3rd digit 2 is the power of 10 factor. The calculation is $ 43 \times 10^2 = 4300 \Omega $
Example: A resitor Blue,Yellow,Red,Brown,Brown, so the digits are 6,4,2,1,1. The value is given by $ 642 \times 10^1 \pm 1 \% = 6420 \Omega ± 1 \% $
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How to read the value of the multiplicator band?
A multiplier ring of value $ n $ corresponds to a multiplication by $ 10^n $ (the corresponding power of 10). This is equivalent to multiply $ n $ times by 10, or to add $ n $ zeros.
Example: If the multiplier ring gives the number 3, then multiply the value given by the first rings by $ 10^3 = 1000 $.
If this ring is of gold color, the value is divided by 10, and for the color silver, divide by 100.
Why is there a difference between theoretical and measured value?
The measured value is never exact but must be in the tolerance interval of the resistor.
Example: A resistor of 100 Ω with a tolerance of 5% could be measured between 95 Ω and 105 Ω.
How to compute the tolerance interval?
The tolerance interval of a resistor is calculated by a percentage of the theoretical value. The percentage applies in plus or minus of the value.
Example: A resistor of 220 ohms Ω with a tolerance of 10%. The value of the tolerance is therefore $ 220 \times 10\% = 22 $. The tolerance interval is therefore $ 220 \pm 22 $, the value is between 198 and 242, sometimes noted $ [ 198, 242 ] $.
How to know the reading direction for colors of a resistor?
The more often, the first band is the closest to the edge. The tolerance band is sometime more spaced than the previous ones (sometimes it is placed on the bump of the resistor).
How to write the value of a resistor?
Generally prefixes are used for values in Ohm (symbol Ω U+2126, coming from the greek letter Ω U+03A9), k for kilo (10^3) and M for mega (10^6).
Example: 12000 Ω = 12 kΩ
Example: 3400000 Ω = 3.4 MΩ
Does a 3 band resistor exists?
A resistor has a minimum of 4 bands, but sometimes, the last band is absent. As it is only about tolerance of the value found with the first 3 bands, take the highest tolerance value: 20%
Why can't a resistor start with a black band?
The black band indicates the value zero, but 0 in the first significant digit is illogical, therefore forbidden according to the standards.
To obtain a resistance lower than 1 ohm, a power band of 10 negative (gold or silver) must be used.
Why can't a resistor end with a black band?
From 4 bands, the last band indicates the tolerance. The black band being associated with the zero value, this means zero tolerance, which is physically impossible.
For a 3-band resistor (without tolerance displayed), the black band in the last position is accepted.
What are mnemonics tricks to remember colors?
Some mnemonicssentences can help to remember the colors and their values. (Some include tolerance bands Gold, Silver or None).
Example: B.B. ROY Goes Bombay Via Gateway With Genelia and Susanne.
B. (BLACK) B. (BROWN) ROY (RED-ORANGE-YELLOW) Goes (GREEN) Bombay (BLUE) Via (VIOLET) Gateway (GREY) With (WHITE) Genelia (GOLD) and Susanne (SILVER).
Example: Bad Beer Rots Our Young Guts But Vodka Goes Well – Get Some Now.
Bad (BLACK) Beer (BROWN) Rots (RED) Our (ORANGE) Young (YELLOW) Guts (GREEN) But (BLUE) Vodka (VIOLET) Goes (GREY) Well (WHITE) – Get (GOLD) Some (SILVER) Now (NONE).
Example: Big Boys Race Our Young Girls But Violet Generally Wins.
Big (BLACK) Boys (BROWN) Race (RED) Our (ORANGE) Young (YELLOW) Girls (GREEN) But (BLUE) Violet (VIOLET) Generally (GREY) Wins (WHITE).
Example: Better Be Right Or Your Great Big Venture Goes West.
Better (BLACK) Be (BROWN) Right (RED) Or (ORANGE) Your (YELLOW) Great (GREEN) Big (BLUE) Venture (VIOLET) Goes (GREY) West (WHITE).
Example: Better Be Right Or Your Great Big Vacation Goes Wrong.
Better (BLACK) Be (BROWN) Right (RED) Or (ORANGE) Your (YELLOW) Great (GREEN) Big (BLUE) Vacation (VIOLET) Goes (GREY) Wrong (WHITE).
Example: Big Brown Rabbits Often Yield Great Big Vocal Groans When Gingerly Slapped Needlessly
Big (BLACK) Brown (BROWN) Rabbits (RED) Often (ORANGE) Yield (YELLOW) Great (GREEN) Big (BLUE) Vocal (VIOLET) Groans (GREY) When (WHITE) Gingerly (GOLD) Slapped (SILVER) Needlessly (NONE)
What is a SMD code?
Resistors tend to get smaller and smaller with the miniaturization of circuit boards. The use of cylindrical resistors tends to disappear in favor of completely flat surface-mounted components (SMD). The colors are no longer used but replaced by an inscription of 3 or 4 digits (which actually correspond to the colors of the rings).
Why this component is called a resistor?
The role of a resistance is to withstand/resist the passage of the current. The higher the value of a resistor, the more it resists the current flow in an electronic circuit.
What is R=V/I formula?
The formula R=V/I is an expression of Ohm's law (also written V=RI), a fundamental law of electricity which describes the relationship between voltage (V), current intensity (I), and the electrical resistance (R) in an electrical circuit.
R: Electrical resistance, measured in ohms (Ω).
V: Voltage, measured in volts (V).
I: Current intensity, measured in amperes (A).
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Resistors' Color Code on dCode.fr [online website], retrieved on 2024-12-21,
- 3-Band Resistor Calculator
- 4 band resistor calculator
- 5 band resistor calculator
- 6 band resistor calculator
- What is a resistor? (Definition)
- How to calculate the value of a resistor?
- How to read the value of the multiplicator band?
- Why is there a difference between theoretical and measured value?
- How to compute the tolerance interval?
- How to know the reading direction for colors of a resistor?
- How to write the value of a resistor?
- Does a 3 band resistor exists?
- Why can't a resistor start with a black band?
- Why can't a resistor end with a black band?
- What are mnemonics tricks to remember colors?
- What is a SMD code?
- Why this component is called a resistor?
- What is R=V/I formula?
