Resistors use a system of colored bands to indicate their resistance value, tolerance, and sometimes temperature coefficient. To read them, orient the resistor with the tolerance band (usually gold, silver, or a wider gap) to the right.
Resistor Color Code Chart
| Color | Digit | Multiplier | Tolerance | Temp. Coeff. (PPM/K) |
|---|
| Black | 0 | x1 Ω | - | 250 |
| Brown | 1 | x10 Ω | ±1% | 100 |
| Red | 2 | x100 Ω | ±2% | 50 |
| Orange | 3 | x1 kΩ | - | 15 |
| Yellow | 4 | x10 kΩ | - | 25 |
| Green | 5 | x100 kΩ | ±0.5% | 20 |
| Blue | 6 | x1 MΩ | ±0.25% | 10 |
| Violet | 7 | x10 MΩ | ±0.1% | 5 |
| Gray | 8 | x100 MΩ | ±0.05% | 1 |
| White | 9 | - | - | - |
| Gold | - | x0.1 Ω | ±5% | - |
| Silver | - | x0.01 Ω | ±10% | - |
Calculation Formulas
The resistance value is calculated based on the first few bands, which represent significant digits, followed by a multiplier band.
- 4-Band Resistor: (1st Digit * 10 + 2nd Digit) * Multiplier
- 5-Band Resistor: (1st Digit * 100 + 2nd Digit * 10 + 3rd Digit) * Multiplier
The Tolerance band indicates the acceptable range of the resistance value. For example, a 1000Ω resistor with a ±5% tolerance can have a value between 950Ω and 1050Ω.
The Temperature Coefficient (found on 6-band resistors) indicates how much the resistance changes as the temperature changes, measured in parts per million (PPM) per degree Kelvin (°K).
What if my resistor only has 3 bands?
A 3-band resistor is similar to a 4-band one, but it lacks a tolerance band. The tolerance is assumed to be ±20%.
How do I know which end to start reading from?
There is often a larger gap between the multiplier/tolerance band and the first digit band. Additionally, tolerance bands are most commonly gold or silver. You should place these to the right before reading.
What are SMD resistors?
Surface-Mount Device (SMD) resistors are smaller and use a numerical code (like 102, 4R7) instead of color bands. This calculator is for through-hole resistors with color bands only.
