Resistor Color Code Calculator

Hold the resistor so the gold or silver tolerance band is on the right. Read left to right: the first two bands are digits, the third is the multiplier (a power of 10), and the fourth is tolerance. Example: brown, black, red, gold is 1, 0, x100, plus or minus 5 percent, which equals 1 kOhm.

4-band gives you 2 significant digits and is the everyday standard. 5-band adds a third digit for precision parts (1 percent and tighter). 6-band keeps the 5-band layout and adds a temperature coefficient in ppm/C, which tells you how much the resistance drifts when the part heats up.

Convention. Manufacturers print the tolerance band slightly offset from the digit and multiplier bands so you can tell which end to read from. If the bands are spaced evenly with no gap, look for gold or silver: those colors only appear in the tolerance (or multiplier) slot, never as a digit.

As a multiplier, gold means times 0.1 and silver means times 0.01, used for sub-ohm values like 0.47 Ohm. As a tolerance band, gold means plus or minus 5 percent and silver means plus or minus 10 percent. Neither color is ever a digit band.

Real resistors are sold in E-series preferred values (E12, E24, E96, E192). The calculator decodes any band combination, including non-standard ones used in legacy or custom parts, so you might see a value like 23 kOhm that no shop stocks. Measure with a multimeter to confirm, since the bands describe the nominal value, not the actual measured resistance.