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How to read Resistor Bands
Most resistors have 4 colored bands printed on them that represent their resistance. Although resistors come in all different sizes and shapes, being able to read the bands will allow you to pick out your needed resistors faster (faster than picking up a random one and checking it with a multimeter until you get lucky).
If you look at a resistor (eg. the ones pictured above), you'll see one band off by itself, away from the other three. That is the right most band (the fourth band; the tolerance band). Starting from the left most band, each represents the following:
- First Number
- Second Number
- Multiplier
- Tolerance
From this, you can see that no resistor can have more than two significant digits. This means that you cannot have a 339 Ohm resistor by itself. In order to get that resistance, you would have to put smaller resistors in series. So, if your numbers come out to be 1, 0, 1k, and 1%, you have a 10k Ohm resistor (1% tolerance).
Here is the table needed to decipher the bands:
| Color | First # | Second # | Multiplier | Tolerance |
| Black | 0 | 0 | 1 | |
| Brown | 1 | 1 | 10 | +/- 1% (F) |
| Red | 2 | 2 | 100 | +/- 2% (G) |
| Orange | 3 | 3 | 1k | |
| Yellow | 4 | 4 | 10k | |
| Green | 5 | 5 | 100k | +/- 0.5% (D) |
| Blue | 6 | 6 | 1M | +/- 0.25 (C) |
| Violet | 7 | 7 | 10M | +/- 0.1 (B) |
| Gray | 8 | 8 | 100M | +/- 0.05 (A) |
| White | 9 | 9 | 1000M |
Additionally, there are three more possible tolerance bands:
- Gold: +/- 5% (J)
- Silver: +/- 10% (K)
- None: +/- 20% (M)
Examples: (minus tolerance bands)
RED, BLUE, BROWN: [2], [6], [10] which means 26 x 10 = 260 Ohms
YELLOW, VIOLET, RED: [4], [7], [100] which means 47 x 100 = 4700 or 4.7k Ohms
YELLOW, YELLOW, YELLOW: [4], [4], [10k] which means 44 x 10k = 440k Ohms