From time to time I get a question about a 5 band resistor that does not enter into the 5-Band calculator we have on the Digi-Key site.
Here we have an example.
No matter if the blue or the black were the first line the bands would not enter correctly into the 5 band calculator. This resistor does work however in the 4-band calculator. Blue, Gray, Silver, Gold.
Now leaves a couple of questions that need to be answered. How do I tell if my resistor is a 4 band or a 5 band? If my 5 band is a 4 band then what is the 5th band?
One key indicator is to look for a gap in the bands. Most resistor companies will put a slightly larger gap between the multiplier and the tolerance gap then between the other bands. Here is an example from Yageo showing a 4 band resistor with a special band.
Here is a similar resistor showing a 5 band from Bourns. Though not as pronounced you can see there is a slightly larger gap between the Multiplier and the Tolerance band.
Now that you have identified that you have a 4 band resistor with a 5th band you want to know what it is calling out. This can also be a bit tricky.
Per IEC 60062:2016 the standard color code would call out Temp Coefficient.
This is not always the case. Yageo for instance uses a Black 5th band in certain series to call out non-inductance.
Trying to identify which you have can range from hard to impossible. If it is a color it is most likely a temp coefficient IEC 60062:2016. If your 5th band is black you are best to try to identify the resistor manufacturer and look at their data sheet.