The Resistor Color Code Calculator reads the coloured bands on any standard 4-band through-hole resistor and converts them into a resistance value in ohms, kilohms, or megohms. Select each band colour from the dropdown — first digit, second digit, multiplier, and tolerance — and see the decoded value with its tolerance range. Includes the full colour code chart and BB ROY mnemonic for quick reference.
Resistor Color Code Calculator
Select band colours to decode resistor value, or enter a value to find the colour code.
How Resistor Color Code Calculator Works
Standard through-hole resistors mark their resistance value with colored bands instead of printed numbers. This calculator decodes a 4-band resistor by combining the two digit bands into a base number, scaling that by the multiplier band, and applying the tolerance band to show the acceptable value range.
Formula: Resistance = (Band 1 digit × 10 + Band 2 digit) × Band 3 multiplier. Tolerance range = Resistance × (1 − Band 4 tolerance ÷ 100) to Resistance × (1 + Band 4 tolerance ÷ 100).
- Band 1 — first significant digit, from Brown (1) through White (9)
- Band 2 — second significant digit, from Black (0) through White (9)
- Band 3 — multiplier band, from Black (×1) up to Blue (×1,000,000), or Gold (×0.1) and Silver (×0.01) for sub-10 ohm values
- Band 4 — tolerance band, Gold (±5%), Silver (±10%), Brown (±1%), or Red (±2%)
Example Scenarios
| Band 1 | Band 2 | Multiplier | Tolerance | Resistance |
|---|---|---|---|---|
| Yellow (4) | Violet (7) | Red (×100) | Gold (±5%) | 4.7 kΩ (4,465–4,935 Ω) |
| Brown (1) | Black (0) | Brown (×10) | Gold (±5%) | 100 Ω (95–105 Ω) |
| Red (2) | Red (2) | Orange (×1K) | Silver (±10%) | 22 kΩ (19,800–24,200 Ω) |
| Green (5) | Blue (6) | Black (×1) | Brown (±1%) | 56 Ω (55.44–56.56 Ω) |
| Orange (3) | Orange (3) | Yellow (×10K) | Gold (±5%) | 330 kΩ (313,500–346,500 Ω) |
| Brown (1) | Black (0) | Gold (×0.1) | Gold (±5%) | 1 Ω (0.95–1.05 Ω) |
Resistor Color Code Calculator FAQ
How do I read a 4-band resistor?
Orient the resistor so the tolerance band (usually gold or silver) is on the right. Read the remaining bands left to right: first digit, second digit, then the multiplier band, which tells you how many zeros to add or what fraction to scale by.What does the multiplier band actually do?
It scales the two-digit base number formed by bands 1 and 2. For example, Black means ×1 (no change), Orange means ×1,000, and Gold or Silver mean ×0.1 or ×0.01 for resistances under 10 ohms.What is the tolerance band and why does it matter?
The tolerance band tells you how far the resistor’s actual resistance may vary from its labeled value, expressed as a percentage. A 4.7kΩ resistor with a gold (±5%) tolerance band could measure anywhere from about 4,465 to 4,935 ohms and still be within spec.What’s an easy way to remember the resistor color order?
A common mnemonic is “BB ROY of Great Britain has a Very Good Wife,” which maps to Black, Brown, Red, Orange, Yellow, Green, Blue, Violet, Grey, White — the digit values 0 through 9 in order.Does this calculator work for 5-band or 6-band resistors?
No, this tool is built specifically for standard 4-band resistors (two digits, one multiplier, one tolerance). 5-band and 6-band resistors add a third digit band for extra precision, and sometimes a temperature coefficient band, which changes how the value is decoded.Why do gold and silver appear as both multiplier and tolerance colors?
Gold and silver serve different roles depending on which band position they’re in. In the multiplier position they represent fractional scale factors (×0.1 and ×0.01), while in the tolerance position they indicate the resistor’s precision (±5% and ±10%).Related Calculators
Once you know a resistor’s value, the Ohm’s Law calculator can help you work out voltage, current, or power in the same circuit. If you’re converting between the multiplier scales used here and standard powers of ten, the scientific notation converter is handy, and the significant figures calculator can help when rounding measured resistance values for a report.