Resistor Color Code

What it is for

The Resistor Color Code tool translates between a resistance and conventional axial resistor color bands. It supports four-band codes with two significant digits and five- or six-band codes with three. You can decode the colors on a part, or enter an exactly representable resistance and generate its bands. The result includes the nominal value, tolerance limits and the IEC 60063 preferred series (E6 to E192) that contain the value. For six bands it also identifies the temperature coefficient.

Select the number of bands first. In decode mode, choose colors in reading order. The third significant digit is used only for five or six bands, and the temperature coefficient is used only for six. In encode mode, enter ohms and choose the tolerance and, for six bands, the temperature coefficient.

Worked example

A resistor with brown, black, red, gold bands has two digits, 1 and 0. Red is the ×100 multiplier, so the nominal resistance is 10 × 100 = 1,000 Ω. Gold means ±5%, giving a nominal tolerance interval of 950 to 1,050 Ω. The tool reports brown · black · red · gold: 1 kΩ ±5% and notes that 1 kΩ belongs to every series from E6 to E192.

To encode a 4.7 kΩ precision resistor, choose five bands, enter 4700 ohms and choose brown tolerance. The result is yellow, violet, black, brown, brown: the digits 4, 7 and 0 followed by a ×10 multiplier and ±1% tolerance. Encoding 4990 Ω instead gives yellow, white, white, brown, brown, and the series list shrinks to E96 and E192 — a typical 1 % value.

For a six-band example, brown, black, black, red, brown, red gives 10,000 Ω ±1% and a 50 ppm/K temperature coefficient. The coefficient is reported separately rather than added to the nominal tolerance limits.

How to read the result

The multiplier changes the value of the significant digits. Gold means ×0.1 and silver means ×0.01; colored multipliers from black to white correspond to powers of ten. The tolerance band describes the allowed deviation from the nominal resistance, not a measured value. The minimum and maximum shown apply that percentage to the nominal value without accounting for temperature.

The sixth band indicates a temperature coefficient, in parts per million per kelvin. A kelvin change has the same size as a degree Celsius change; consult the datasheet for the temperature range.

Preferred series lists the E-series that contain the exact significant digits. A decoded value outside every series often means a misread colour.

Tips and common mistakes

Read from the significant-digit end. A tolerance band is often separated from the other bands, but markings and spacing vary. Lighting, discoloration and small parts can make colors difficult to distinguish; confirm ambiguous bands using the manufacturer’s datasheet or a meter on an isolated component.

Encoding is exact: if two significant digits cannot express a value, the tool reports an error instead of silently changing it. Try a five-band code or deliberately choose a suitable available resistor. A color code does not establish power rating, voltage rating, stock availability or suitability for a circuit. Special military and manufacturer-specific markings, unbanded tolerance, and zero-ohm jumpers are outside this tool.

The mapping follows Vishay’s color-code chart; check the actual part’s datasheet for exceptions.

FAQ

Can I enter kilo-ohms directly?

Enter the numeric resistance in ohms: 4.7 kΩ is 4700 Ω, and 1 MΩ is 1000000 Ω.

Why was my value rejected?

The selected band count provides only two or three significant digits and a limited set of multipliers. The tool does not round to a different value. Choose a representable value or more significant bands.

Does the tolerance range include temperature drift?

No. It shows nominal value plus or minus the marked tolerance. Temperature behavior and the applicable range must be checked separately against the component datasheet.