Resistor Colour Code Calculator
Pick the number of bands and the colours to read the resistance and tolerance. Or type a value to see which colours to look for.
Hold the resistor with the band closest to one end on the left. The tolerance band, often gold or silver, is on the right. A gap before the last band is normal.
Worked examples
Four bands
Yellow, violet, red, gold
4.7 kilohms, plus or minus 5%
47 x 100 ohms.
Five bands
Brown, black, black, red, brown
10 kilohms, plus or minus 1%
100 x 100 ohms.
About Resistor Colour Code Calculator
Resistors are too small for printed numbers, so their value is shown with coloured bands. In a four band resistor the first two bands are digits, the third is a multiplier and the fourth is the tolerance. Five band parts add a third digit for precision resistors, and six band parts add a temperature coefficient. This calculator decodes any of them and draws the resistor so you can check it against the part in your hand.
It also works the other way. Type the value you need, choose the number of bands and a tolerance, and the page lists the colours to look for. If the value cannot be shown exactly with the digits available, for example 4,730 ohms on a four band part, the page tells you the nearest value the bands can show, so you do not waste time hunting for a part that does not exist.
How to use Resistor Colour Code Calculator
- Choose whether to read the colours or find the colours for a value, and the number of bands.
- To read a resistor, pick the colour of each band from the menus, starting at the end with the bands closest to the edge.
- To find colours, enter the resistance, pick the unit and the tolerance.
- Read the value, the tolerance range and the picture, or the list of colours to look for.
Common uses
- Identifying a loose resistor from a parts bin
- Finding the right band colours when ordering or sorting parts
- Checking a resistor before soldering it into a kit
- Learning the colour code for electronics classes
Frequently asked questions
How do I know which end to read from?
Start from the end where the bands are closest together and nearest to the edge. The tolerance band, often gold or silver, is separated by a slightly larger gap and sits on the right. If in doubt, check both ways with a meter.
What do gold and silver mean?
In the multiplier position gold means times 0.1 and silver times 0.01. In the tolerance position gold means plus or minus 5% and silver plus or minus 10%.
What is the sixth band?
The sixth band on a six band resistor gives the temperature coefficient in parts per million per kelvin, such as 50 ppm for red. It says how much the value drifts as the part warms or cools.
Why does my meter read a different value?
The value is within the tolerance, and a resistor in a circuit reads low because other parts are in parallel with it. Remove one end from the board to test it properly.