What Is a Resistor Color Code Calculator?
This calculator decodes a 4-band resistor's color code into its resistance value and tolerance — the standard method for reading fixed-value resistors used in electronics without needing a multimeter.
How to Use the Resistor Calculator
- Select the color of each band, reading left to right on the physical resistor.
- View the decoded resistance value and tolerance.
Resistor Color Code Formula
Standard Color Code Reference
| Color | Digit | Multiplier |
|---|---|---|
| Black | 0 | ×1 |
| Brown | 1 | ×10 |
| Red | 2 | ×100 |
| Orange | 3 | ×1,000 |
| Yellow | 4 | ×10,000 |
| Green | 5 | ×100,000 |
| Blue | 6 | ×1,000,000 |
| Violet | 7 | – |
| Gray | 8 | – |
| White | 9 | – |
| Gold | – | ×0.1 |
| Silver | – | ×0.01 |
Worked Example
Band 1 (Brown) = 1, Band 2 (Black) = 0 → 10
Band 3 (Red) = ×100 multiplier
Resistance: 10 × 100 = 1,000 Ω (1 kΩ)
Band 4 (Gold) = ±5% tolerance
Understanding Your Results
The first two bands form the base digits, the third band is the multiplier (power of 10), and the fourth band indicates tolerance (how much the actual resistance may vary from the labeled value).
Frequently Asked Questions
Read the bands left to right: the first two bands give the significant digits, the third band is the multiplier, and the fourth band indicates tolerance.
It indicates how much the actual resistance may vary from the labeled (nominal) value — for example, a gold tolerance band means ±5%.
Start from the end with bands closer together (the tolerance band is usually spaced slightly apart from the others, marking the end to read last).
5-band resistors add an extra digit for higher precision, with three significant digit bands instead of two, before the multiplier and tolerance bands.
Yes — reading the color code (as this calculator decodes) gives you the manufacturer's labeled value without needing to measure it directly.