Resistor Color Code Calculator
This Resistor Color Code Calculator decodes 4-band, 5-band, and 6-band through-hole resistor markings. Select each color in reading order to calculate the nominal resistance, tolerance range, and, for a 6-band part, its temperature coefficient.
It is designed for electronics engineers, technicians, students, repair specialists, and hardware designers who need to identify a resistor before schematic capture, prototyping, inspection, or troubleshooting.
The result includes a human-readable engineering value plus minimum and maximum resistance limits, making it easier to compare a marked component with a multimeter reading or bill-of-materials requirement.
Resistor Color Code Calculator
Select a 4-band, 5-band, or 6-band format and choose each band color. Resistance, tolerance, range, and temperature coefficient update automatically.
Decoded value
4.7 kΩ ±5%
- Resistance value
- 4.7 kΩ
- Tolerance
- ±5%
- Minimum resistance
- 4.465 kΩ
- Maximum resistance
- 4.935 kΩ
Resistor Color Code Formula
4-band resistance: R = AB × M5-band and 6-band resistance: R = ABC × MMinimum resistance: Rmin = R × (1 - T / 100)Maximum resistance: Rmax = R × (1 + T / 100)- AB = Two significant digits for a 4-band resistor
- ABC = Three significant digits for a 5-band or 6-band resistor
- M = Multiplier represented by the multiplier band
- T = Tolerance percentage represented by the tolerance band
How to Use This Calculator
- Identify the reading direction. The tolerance band is commonly gold, silver, brown, or another precision color and is usually separated slightly from the significant bands.
- Choose 4, 5, or 6 bands. Four-band parts use two significant digits; five-band and six-band parts use three significant digits.
- Select each color from left to right. The calculator restricts each selector to colors that are valid for that band role.
- Read the nominal resistance, tolerance, minimum value, maximum value, and optional temperature coefficient from the result area.
Resistor Color Code Chart
A dash means the color is not normally assigned to that function. Gold and silver are valid multipliers and tolerances but not significant digits. Temperature coefficient values apply to the sixth band.
| Color | Digit | Multiplier | Tolerance | Temperature coefficient |
|---|---|---|---|---|
| Black | 0 | ×1 | — | 250 ppm/K |
| Brown | 1 | ×10 | ±1% | 100 ppm/K |
| Red | 2 | ×100 | ±2% | 50 ppm/K |
| Orange | 3 | ×1 k | — | 15 ppm/K |
| Yellow | 4 | ×10 k | — | 25 ppm/K |
| Green | 5 | ×100 k | ±0.5% | 20 ppm/K |
| Blue | 6 | ×1 M | ±0.25% | 10 ppm/K |
| Violet | 7 | ×10 M | ±0.1% | 5 ppm/K |
| Gray | 8 | ×100 M | ±0.05% | 1 ppm/K |
| White | 9 | ×1 G | — | — |
| Gold | — | ×0.1 | ±5% | — |
| Silver | — | ×0.01 | ±10% | — |
Worked Example
A 4-band resistor marked yellow, violet, red, gold uses yellow as 4, violet as 7, red as a ×100 multiplier, and gold as ±5% tolerance.
Nominal resistance: 47 × 100 = 4,700 Ω = 4.7 kΩ.
Minimum resistance: 4,700 × 0.95 = 4,465 Ω.
Maximum resistance: 4,700 × 1.05 = 4,935 Ω.
The complete decoded value is 4.7 kΩ ±5%.
Engineering Notes
- Color decoding identifies nominal resistance, not power rating. Check package dimensions, manufacturer data, or the circuit BOM for wattage.
- Compare measured resistance against the calculated tolerance range, but isolate the resistor from parallel circuit paths before measuring.
- Heat, aging, contamination, and measurement accuracy can move a real reading away from its nominal value even when the color code is clear.
- A lower ppm/K value is important in precision sensing, references, amplifiers, and other circuits where ambient temperature changes matter.
Common Mistakes
- Reading the bands from the tolerance end instead of the digit end.
- Using gold or silver as a significant digit.
- Applying a two-digit formula to a precision 5-band resistor.
- Confusing the sixth temperature coefficient band with tolerance.
- Assuming color code alone identifies resistor power rating.
FAQ
How do you read a resistor color code?
Read from the end where the significant-digit bands are closest to the resistor body edge. Convert the digit bands to a number, apply the multiplier, then read tolerance and temperature coefficient bands.
What is the difference between 4-band and 5-band resistors?
A 4-band resistor uses two significant digits, while a 5-band resistor uses three. The extra digit provides finer resistance-value resolution and is common on precision resistors.
What does the gold or silver band mean?
As a tolerance band, gold means ±5% and silver means ±10%. In the multiplier position, gold means ×0.1 and silver means ×0.01.
What is the temperature coefficient band?
The sixth band states how much resistance may change with temperature in parts per million per kelvin, written as ppm/K. Lower values indicate better temperature stability.
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Reference Links
Continue to the resistor calculators category for related design tools, or use the Engineering Reference Center for component and hardware design resources.
Disclaimer
This calculator provides nominal engineering reference values. Confirm critical components with a calibrated measurement, manufacturer data, circuit documentation, and appropriate design margin before production.