Click on a value to use it:
| Color | Digit | Multiplier | Tolerance | Temp. Coefficient (ppm/K) |
|---|---|---|---|---|
| Black | 0 | 1 Ω | - | - |
| Brown | 1 | 10 Ω | ±1% | 100 |
| Red | 2 | 100 Ω | ±2% | 50 |
| Orange | 3 | 1 kΩ | - | 15 |
| Yellow | 4 | 10 kΩ | - | 25 |
| Green | 5 | 100 kΩ | ±0.5% | 20 |
| Blue | 6 | 1 MΩ | ±0.25% | 10 |
| Violet | 7 | 10 MΩ | ±0.1% | 5 |
| Gray | 8 | 100 MΩ | ±0.05% | 1 |
| White | 9 | 1 GΩ | - | - |
| Gold | - | 0.1 Ω | ±5% | - |
| Silver | - | 0.01 Ω | ±10% | - |
| None | - | - | ±20% | - |
The color bands on a resistor are read from left to right, with the tolerance band (usually gold or silver) positioned on the right side.
10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82
10, 11, 12, 13, 15, 16, 18, 20, 22, 24, 27, 30, 33, 36, 39, 43, 47, 51, 56, 62, 68, 75, 82, 91
100, 102, 105, 107, 110, 113, 115, 118, 121, 124, 127, 130, 133, 137, 140, 143, 147, 150...
The band count tells you the scheme. In a four-band resistor the first two bands are significant digits, the third is the multiplier and the fourth is tolerance. A five-band part uses three significant digits, a multiplier and a tolerance, which is how tighter-tolerance values are encoded. A six-band part adds a temperature coefficient.
| Colour | Digit | Multiplier | Tolerance |
|---|---|---|---|
| Black | 0 | ×1 | — |
| Brown | 1 | ×10 | ±1% |
| Red | 2 | ×100 | ±2% |
| Orange | 3 | ×1k | — |
| Yellow | 4 | ×10k | — |
| Green | 5 | ×100k | ±0.5% |
| Blue | 6 | ×1M | ±0.25% |
| Violet | 7 | ×10M | ±0.1% |
| Grey | 8 | — | ±0.05% |
| White | 9 | — | — |
| Gold | — | ×0.1 | ±5% |
| Silver | — | ×0.01 | ±10% |
This is the most common mistake, and there is a reliable rule: the tolerance band is usually gold or silver, and it sits slightly further from the others. Put that band on the right. If neither gold nor silver appears, the wider gap before the last band marks the tolerance end.
Reading a 4.7 kΩ ±5% part (yellow-violet-red-gold) backwards gives gold-red-violet-yellow, which is not a valid code at all — so a reversed reading often announces itself. But some codes are valid both ways round, and those are the ones that cause real trouble. When in doubt, measure.
Bands remain readable whatever the orientation of a small cylindrical part on a board, and they survive the heat and solvents of manufacturing better than printed text. The system dates from a time when axial components were inserted by hand in any orientation, and it has stayed because it still works. Surface-mount parts, which sit flat with a visible top face, use printed numeric codes instead.
The tolerance band is usually gold or silver and sits slightly further from the rest. Place it on the right and read from the opposite end. If no gold or silver band is present, look for the wider gap before the final band.
Four-band uses two significant digits plus a multiplier and tolerance. Five-band uses three significant digits, which allows tighter tolerance values to be encoded precisely.
As the last band it indicates ±5% tolerance. In the multiplier position it means ×0.1, which is how sub-ohm values such as 0.47 Ω are encoded.
The temperature coefficient in parts per million per degree Celsius. It appears on precision resistors where the value must remain stable across the operating temperature range.
Measure it. Bands fade with age and heat, brown and red are easily confused on a small part, and a burnt resistor may have discoloured entirely. A meter reading settles the question in seconds.
Because they sit flat with a visible top surface that can carry printed text, so a numeric code is readable without needing orientation-independent markings.