Resistor color codes

The resistor color code is used to indicate the value of through hole resistors below 1 Watt. Surface mount resistor markings are generally an alphanumeric code. On large power resistors and potentiometers the value is usually given explicitly. The codes are defined in IEC 60062.

Preferred values

Resistors are available mainly in two series of preferred values, E12 (12 values per decade) and E24 (24 values per decade). Carbon resistors with a tolerance 5% and less are available in the E12 series while metal film resistors with 2% and better tolerance are available in the E24 series.

Help to remember

Without a mnemonic: Black is darkest, brown is a dark shade of red, then the color spectrum ROY G. BV, then grey as colour is lost, and white is brightest. Gold has a better value than silver.

How to read

The first band is closest to one end. If there is a gap between bands 3 and 4, band 4 is the tolerance. Gold or silver gives the tolerance and the tolerance is usually the last band. Pink for the tolerance band shows it's ±20%.

A resistor with a single black band is a zero-ohm resistor and can be replaced by a wire link.

Colour chart for 4, 5 and 6 bands resistors

Approximate power rating of through hole resistor sizes

There is no standard specification for power rating of particular through hole resistor sizes. Only the seller or data sheet for a specific resistor can confirm its power rating.

Key resistor dimensions

Carbon film

Watts Length (mm) Diameter (mm)
1/8 3.5 1.85
1/4 6.8 2.5
1/2 10.0 3.5
1W 16.0 5.5
2W 17.5 6.5

[1]

Metal film

Watts Length (mm) Diameter (mm)
1/8 3.5 1.85
1/4 6.8 2.5
1/2 10.0 3.5
1 12.0 5,0
2 16.0 5.5
3 17.5 6.5

[2]

See also

Notes

References

  1. ^ Carbon film fixed resistors, Royal Ohm, 18 Aug 2018
  2. ^ Precision metal film fixed resistors, Royal Ohm, 18 Aug 2018

Further reading

  • A Users Guide to Selecting Electronic Components by Gerald L Ginsberg, John Wiley & Sons Inc, 1981, ISBN 0-471-08308-9
  • Passive Components: a user's guide by Ian Robertson Sinclair, Butterworth-Heinemann Ltd, 1991, ISBN 0-7506-0229-5

External links