## How to read Resistor Colour Codes

**First the code**

**Black Brown Red Orange Yellow Green Blue Violet Grey White**

**0****1****2****3****4****5****6****7****8****9****Then the mnemonic**

Big Boys Race Only Young Girls But Violet Generally Wins

(There are others but many are not suitable for publication)

Black is also easy to remember as zero because of the nothingness common to both.

**How to read the code**

- First find the tolerance band, it will typically be gold ( 5%) and sometimes silver (10%).

- Starting from the other end, identify the first band - write down the number associated with that colour; in this case Blue is 6.

- Now 'read' the next colour, here it is red so write down a '2' next to the six. (you should have '62' so far.)

- Now read the third or 'multiplier exponent' band and write down that as the number of zeros.

- In this example it is two so we get '6200' or '6,200'. If the 'multiplier exponent' band is Black (for zero) don't write any zeros down.

- If the 'multiplier exponent' band is Gold move the decimal point one to the left. If the 'multiplier exponent' band is Silver move the decimal point two places to the left. If the resistor has one more band past the tolerance band it is a quality band.

- Read the number as the '% Failure rate per 1000 hour' This is rated assuming full wattage being applied to the resistors. (To get better failure rates, resistors are typically specified to have twice the needed wattage dissipation that the circuit produces). 1% resistors have three bands to read digits to the left of the multiplier. They have a different temperature coefficient in order to provide the 1% tolerance.

- At 1% the temperature coefficient starts to become an important factor. at +/-200 ppm a change in temperature of 25 Deg C causes a value change of up to 1%

**BS 1852 Coding for resistor values**

BS 1852(British Standard 1852). The letter R is used for Ohms and K for Kohms M for Megohms and placed where the decimal point would go.

At the end is a letter that represents tolerance Where M=20%, K=10%, J=5%, G=2%, and F=1% D=.5% C=.25% B=.1%

BS 1852 coding examples

R33 0.33 ohms

2R2 2.2 ohms

470R 470 Ohms

1K2 1.2K ohms

22K 22K ohms

22K2 22.2K ohms

4M7 4.7M ohms

5K6G 5.6K ohms 2%

33KK 33k Ohms 10%

47K3F 47.3 K Ohms 1%

(c) Stephen Rand 2009 - 2017