How to read a resistor color code
Hold the resistor so the tolerance band (usually gold or silver, often set slightly apart) is on the right. Read the colors from the left. The color code is defined in IEC 60062.
- 4 bands: digit, digit, multiplier, tolerance.
- 5 bands: digit, digit, digit, multiplier, tolerance (precision resistors, usually 1%).
- 6 bands: like 5 bands plus a temperature coefficient in ppm/K.
Worked example
Yellow (4), violet (7), red (×100), gold (±5%): 47 × 100 = 4,700 Ω = 4.7 kΩ. The real value may be anywhere from 4,465 Ω to 4,935 Ω. A 5-band brown-black-black-red-brown resistor is 100 × 100 = 10 kΩ ±1% (9.9 kΩ to 10.1 kΩ).
Standard values (E-series)
Resistors are made in the preferred-number series of IEC 60063: E12 (10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82) for 10% parts, E24 for 5% and E96 for 1%. If a reading gives a value that is not in any series, you are probably reading the resistor backwards.
Frequently asked questions
Which side do I start reading a resistor from?
Start from the end opposite the gold or silver band. On 5-band resistors the tolerance band (often brown) is usually spaced a little further from the others.
What color is a 10k resistor?
Brown, black, orange, gold on a 4-band resistor (10 × 1,000 Ω, ±5%), or brown, black, black, red, brown on a 5-band 1% resistor.
What does a 6th band mean?
It is the temperature coefficient: how much the resistance drifts per kelvin, in ppm/K. Brown means 100 ppm/K, red 50 ppm/K.