Resistor Color Code

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6 band resistor color code

6 Band Resistor Color Code

The sixth band is the odd one out. The first four give the resistance, the fifth tells you how far a part may start from that value, and the sixth tells you how much it moves when the temperature changes. Brown, black, black, red, brown, red is a 10 kΩ part, ±1%, at 50 ppm/K.

From color to ppm/K, and from ppm/K to ohms

ppm/K stands for parts per million per kelvin. The change in resistance comes from ΔR = R × ppm × 10^-6 × ΔT. For a 10 kΩ resistor at 100 ppm/K (brown) warming by 50 K, the math is 10,000 × 100 × 0.000001 × 50 = 50 Ω. At 50 ppm/K (red) the same warming moves it only 25 Ω. Because the formula is linear, doubling the coefficient doubles the drift, and so does doubling the temperature change.
The sixth-band values are black 250, brown 100, red 50, orange 15, yellow 25, green 20, blue 10, violet 5 and grey 1 ppm/K. Notice that yellow (25) is higher than orange (15), so rainbow order does not follow coefficient order. Over the same 50 K swing, a 10 kΩ black part (250 ppm/K) moves 125 Ω, a violet one (5 ppm/K) moves 2.5 Ω, and a grey one (1 ppm/K) only 0.5 Ω.
Set the drift against the tolerance window. At ±1%, the 10 kΩ part may already leave the factory anywhere between 9,900 Ω and 10,100 Ω, which is 100 Ω either side. A 50 Ω drift at 100 ppm/K eats half of that margin. In a circuit that sits at room temperature, the sixth band can be ignored. In a precision divider or a reference inside a warm enclosure, it deserves as much attention as the tolerance band.

Six bands read end to end

10 kΩ at 50 ppm/K

Input: brown-black-black-red-brown-red
Expected output: 10k ±1% 50ppm/K

100 × 100 = 10,000 Ω. Over 50 K the drift is 10,000 × 50 × 10^-6 × 50 = 25 Ω.

10 kΩ at 100 ppm/K

Input: brown-black-black-red-brown-brown
Expected output: 10k ±1% 100ppm/K

Same value, brown sixth band: twice the coefficient, so 50 Ω of drift over 50 K.

2.2 kΩ at 15 ppm/K

Input: red-red-black-brown-brown-orange
Expected output: 2k2 ±1% 15ppm/K

220 × 10 = 2,200 Ω. Orange is 15 ppm/K: over 50 K the shift is 1.65 Ω, far below the ±22 Ω of tolerance.

100 kΩ, ±0.5% and 10 ppm/K

Input: brown-black-black-orange-green-blue
Expected output: 100k ±0.5% 10ppm/K

100 × 1,000 = 100,000 Ω. Green is ±0.5% and blue is 10 ppm/K, which gives 50 Ω of drift over 50 K.

4.7 kΩ at 5 ppm/K

Input: yellow-violet-black-brown-brown-violet
Expected output: 4k7 ±1% 5ppm/K

470 × 10 = 4,700 Ω. Violet is 5 ppm/K, and 4,700 × 5 × 10^-6 × 50 comes to about 1.2 Ω.

Full tool FAQ

Which end do I start reading a resistor's bands from?

Start from the end opposite the tolerance band. The tolerance band is usually gold or silver (or visibly set apart from the rest with a wider gap), so it's always read last, and tells you which end to begin at.

Why do gold and silver never represent a digit?

What's the difference between 4-, 5- and 6-band resistors?

Is there a trick to memorize the color order?

What does a resistor's tolerance actually mean in practice?

Frequently asked questions

What does the sixth band on a resistor mean?

It is the temperature coefficient, in ppm/K. It tells you how much the resistance changes for every kelvin of temperature change. It does not alter the nominal value you read from the other bands.

How do I calculate how far the resistor will drift?

Multiply the value by the coefficient in ppm, by 10^-6 and by the temperature change. For 4.7 kΩ at 5 ppm/K and 40 K of warming: 4,700 × 5 × 10^-6 × 40 = 0.94 Ω.

Which sixth-band color is the most stable?

Grey, at 1 ppm/K. At the other extreme sits black, at 250 ppm/K, which moves 250 times more per kelvin.

Is a 6 band reading different from a 5 band one?

No. The first five bands read exactly as on a five-band part (three digits, multiplier, tolerance), and the sixth is simply added at the end.

Next steps

From color to ppm/K, and from ppm/K to ohms

ppm/K stands for parts per million per kelvin. The change in resistance comes from ΔR = R × ppm × 10^-6 × ΔT. For a 10 kΩ resistor at 100 ppm/K (brown) warming by 50 K, the math is 10,000 × 100 × 0.000001 × 50 = 50 Ω. At 50 ppm/K (red) the same warming moves it only 25 Ω. Because the formula is linear, doubling the coefficient doubles the drift, and so does doubling the temperature change.

The sixth-band values are black 250, brown 100, red 50, orange 15, yellow 25, green 20, blue 10, violet 5 and grey 1 ppm/K. Notice that yellow (25) is higher than orange (15), so rainbow order does not follow coefficient order. Over the same 50 K swing, a 10 kΩ black part (250 ppm/K) moves 125 Ω, a violet one (5 ppm/K) moves 2.5 Ω, and a grey one (1 ppm/K) only 0.5 Ω.

Set the drift against the tolerance window. At ±1%, the 10 kΩ part may already leave the factory anywhere between 9,900 Ω and 10,100 Ω, which is 100 Ω either side. A 50 Ω drift at 100 ppm/K eats half of that margin. In a circuit that sits at room temperature, the sixth band can be ignored. In a precision divider or a reference inside a warm enclosure, it deserves as much attention as the tolerance band.

Six bands read end to end

10 kΩ at 50 ppm/K

Input: brown-black-black-red-brown-red
Expected output: 10k ±1% 50ppm/K

100 × 100 = 10,000 Ω. Over 50 K the drift is 10,000 × 50 × 10^-6 × 50 = 25 Ω.

10 kΩ at 100 ppm/K

Input: brown-black-black-red-brown-brown
Expected output: 10k ±1% 100ppm/K

Same value, brown sixth band: twice the coefficient, so 50 Ω of drift over 50 K.

2.2 kΩ at 15 ppm/K

Input: red-red-black-brown-brown-orange
Expected output: 2k2 ±1% 15ppm/K

220 × 10 = 2,200 Ω. Orange is 15 ppm/K: over 50 K the shift is 1.65 Ω, far below the ±22 Ω of tolerance.

100 kΩ, ±0.5% and 10 ppm/K

Input: brown-black-black-orange-green-blue
Expected output: 100k ±0.5% 10ppm/K

100 × 1,000 = 100,000 Ω. Green is ±0.5% and blue is 10 ppm/K, which gives 50 Ω of drift over 50 K.

4.7 kΩ at 5 ppm/K

Input: yellow-violet-black-brown-brown-violet
Expected output: 4k7 ±1% 5ppm/K

470 × 10 = 4,700 Ω. Violet is 5 ppm/K, and 4,700 × 5 × 10^-6 × 50 comes to about 1.2 Ω.

Full tool FAQ

Which end do I start reading a resistor's bands from?

Why do gold and silver never represent a digit?

What's the difference between 4-, 5- and 6-band resistors?

Is there a trick to memorize the color order?

What does a resistor's tolerance actually mean in practice?

Frequently asked questions

What does the sixth band on a resistor mean?

It is the temperature coefficient, in ppm/K. It tells you how much the resistance changes for every kelvin of temperature change. It does not alter the nominal value you read from the other bands.

How do I calculate how far the resistor will drift?

Multiply the value by the coefficient in ppm, by 10^-6 and by the temperature change. For 4.7 kΩ at 5 ppm/K and 40 K of warming: 4,700 × 5 × 10^-6 × 40 = 0.94 Ω.

Which sixth-band color is the most stable?

Grey, at 1 ppm/K. At the other extreme sits black, at 250 ppm/K, which moves 250 times more per kelvin.

Is a 6 band reading different from a 5 band one?

No. The first five bands read exactly as on a five-band part (three digits, multiplier, tolerance), and the sixth is simply added at the end.