Related Tool: Ohm's Law Calculator
Resistor Color Code
An electronic color code is a code that is used to specify the ratings of certain electrical components, such as the resistance in Ohms of a resistor. Electronic color codes are also used to rate capacitors, inductors, diodes, and other electronic components, but are most typically used for resistors.
How the Color Coding Works
The color coding for resistors is an international standard defined in IEC 60062. The resistor color code involves various colors that represent significant figures, a multiplier, tolerance, reliability, and temperature coefficient. Which of these the color refers to is dependent on the position of the color band on the resistor. In a typical four-band resistor, there is a spacing between the third and the fourth band to indicate how the resistor should be read (from left to right, with the lone band after the spacing being the right-most band).
- Significant Figure Component: In a typical four-band resistor, the first and second bands represent significant figures. For example, a green band (5) followed by a red band (2) yields the base value of 52.
- Multiplier: The third band is the multiplier. If the third band is blue (1,000,000), you multiply the base value by the multiplier (52 × 1,000,000 = 52,000,000 Ω or 52 MΩ).
- Tolerance: The fourth band represents tolerance, which is a percentage by which the resistor value can vary. A gold band indicates a tolerance of ±5%, meaning a 52 MΩ resistor's true value lies between 49.4 MΩ and 54.6 MΩ.
- Other Variations: Components made to military specs may have a fifth band indicating failure rate percentage. Some 5-band resistors use the first three bands for significant figures to provide more precision. A 6th band, if present, usually indicates the temperature coefficient (change in resistance based on ambient temperature in ppm/K).
| Color | 1st, 2nd, 3rd Band (Significant Figures) | Multiplier | Tolerance | Temperature Coefficient |
|---|---|---|---|---|
| Black | 0 | × 1 | 250 ppm/K (U) | |
| Brown | 1 | × 10 | ±1% (F) | 100 ppm/K (S) |
| Red | 2 | × 100 | ±2% (G) | 50 ppm/K (R) |
| Orange | 3 | × 1K | ±0.05% (W) | 15 ppm/K (P) |
| Yellow | 4 | × 10K | ±0.02% (P) | 25 ppm/K (Q) |
| Green | 5 | × 100K | ±0.5% (D) | 20 ppm/K (Z) |
| Blue | 6 | × 1M | ±0.25% (C) | 10 ppm/K (Z) |
| Violet | 7 | × 10M | ±0.1% (B) | 5 ppm/K (M) |
| Grey | 8 | × 100M | ±0.01% (L) | 1 ppm/K (K) |
| White | 9 | × 1G | ||
| Gold | × 0.1 | ±5% (J) | ||
| Silver | × 0.01 | ±10% (K) | ||
| None | ±20% (M) |
Circuit Arrangements & Conductor Resistance
Resistors are circuit elements that impart electrical resistance. While circuits can be highly complicated, resistors in complex circuits can typically be broken down and classified as being connected in series or in parallel.
Resistors in Parallel
The total resistance of resistors in parallel is equal to the reciprocal of the sum of the reciprocals of each individual resistor.
Resistors in Series
The total resistance of resistors in series is simply the sum of the resistances of each resistor.
Resistance of a Conductor
The resistance of a physical wire or conductor can be calculated if you know its length, cross-sectional area, and the material's conductivity.
Where:
L is the length of the conductor
A is the cross-sectional area of the conductor
C is the conductivity of the material (in S/m)