Resistor Color Code Guide: How to Read Resistor Bands
Learn how to read 4-band, 5-band and 6-band resistor color codes, calculate resistance and tolerance, and convert SMD resistor markings quickly.
How resistor color codes work
Through-hole resistors use colored bands to encode resistance value, multiplier and tolerance. The first significant-figure bands are read from the end closest to a band, the multiplier band shifts the decimal point, and the final band indicates tolerance such as ±5% (gold) or ±1% (brown).
A 4-band resistor provides two significant digits, while a 5-band precision resistor provides three. A 6-band part adds a temperature-coefficient band, typically expressed in ppm/°C.
Reading the value step by step
First orient the resistor so the tolerance band is on the right. Write down the digit for each color band (black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, gray 8, white 9), multiply by the multiplier band, then append the tolerance.
Example — red, red, orange, gold = 22 × 1,000 = 22 kΩ at ±5%. For surface-mount parts, numeric markings such as 104 mean 10 × 10^4 = 100 kΩ.
Frequently Asked Questions
What does a 104 SMD marking mean?
104 means 10 with four added zeros, i.e. 100,000 Ω = 100 kΩ. The third digit is the multiplier (number of zeros).
How do I choose resistor tolerance?
Use ±1% for precision analog and sensing circuits; ±5% general-purpose parts are fine for pull-ups, current limiting and non-critical biasing.