How to Read Resistor Color Codes

A resistor tells you its value with a series of painted rings, not printed numbers, because the part is often too small for legible text. Each color maps to a digit from 0 to 9: black is 0, brown is 1, red is 2, orange is 3, yellow is 4, green is 5, blue is 6, violet is 7, grey is 8, and white is 9.

Most through-hole resistors carry either four or five bands. The first two or three bands are significant digits, the next band is a multiplier (a power of ten), and the final band, usually gold or silver, is the tolerance. Reading them in the wrong order is the single most common mistake, so orientation matters before you decode anything.

On a 4-band part the first band is the first digit, the second band is the second digit, the third band is the multiplier, and the fourth band is tolerance. For example, brown-black-red gives digits 1 and 0, then a multiplier of 100, which is 10 times 100, or 1000 ohms (1 kiloohm). A gold fourth band means plus or minus 5 percent.

The tolerance band is usually gold (5 percent) or silver (10 percent) and sits slightly apart from the other three. That gap is your clue for which end to start from. If you read the resistor backwards you will get a wildly different value, so always put the tolerance band on the right.

Precision resistors add a third significant-digit band, so a 5-band part reads as digit, digit, digit, multiplier, tolerance. Brown-black-black-brown-brown means digits 1, 0, and 0, a multiplier of 10, and a 1 percent tolerance, which works out to 1000 ohms with tight accuracy.

Five-band resistors typically have brown (1 percent) or red (2 percent) tolerance bands, reflecting their higher precision. The extra digit lets manufacturers specify values that a two-digit code cannot represent exactly.

The calculator on this page mirrors the physical part: you pick a color for each band and it shows the resistance, multiplier, and tolerance instantly. Everything runs in your browser, so nothing you enter is uploaded.

Red and orange can look alike under warm lighting, and brown and red confuse many beginners. When in doubt, measure the part with a multimeter and compare the reading to your decoded value. If they disagree by more than the tolerance, you probably swapped a color.

Older or heat-stressed resistors can have faded bands, and some films of dust make grey read as white. Good, neutral lighting and a magnifier solve most of these problems. Remember that a fifth band on the far left, when present, might actually be a temperature-coefficient band rather than an extra digit, so count carefully.