Resistors are normally labelled using 4 coloured bands across the body of the resistor. This consists three bands together indicating the resistance value of the resistor (ohms) and the forth, further away than the first three, is used to indicate the tolerance (accuracy) of the resistor. Some resistors have a 5th band indicating the failure rate of the resistor required for military use.
The bands relate to the resistance as follows:
| Colour | Significant figures | Multiplier | Tolerance |
|---|---|---|---|
| Black | 0 | x100 | - |
| Brown | 1 | x101 | ±1% |
| Red | 2 | x102 | ±2% |
| Orange | 3 | x103 | - |
| Yellow | 4 | x104 | - |
| Green | 5 | x105 | ±0.5% |
| Blue | 6 | x106 | ±0.25% |
| Violet | 7 | x107 | ±0.1% |
| Grey | 8 | x108 | ±0.05% |
| White | 9 | x109 | - |
| Gold | - | x10-1 | ±5% |
| Silver | - | x10-2 | ±10% |
| None | - | - | ±20% |
The example above has colours: Red, Green, Blue ... Silver.
This translates to 2 (red), 5 (green), x106 (blue), with a tolerence of 10%.
which is 25,000,000Ω or 25MΩ.
The tolerence is not normally a major consideration for most circuits, but if the exact value of the resistor is required then that band should be considered as well.
Please view the copyright information regarding use of the circuits.
