Four-band resistors usually come in E12 or E24 values with 5% tolerance.
Resistor color code chart
| Colour | Digit | Multiplier | Tolerance | Temp. coeff. |
|---|---|---|---|---|
| Black | 0 | ×1 | – | 250 ppm/K |
| Brown | 1 | ×10 | ±1% | 100 ppm/K |
| Red | 2 | ×100 | ±2% | 50 ppm/K |
| Orange | 3 | ×1,000 | – | 15 ppm/K |
| Yellow | 4 | ×10,000 | – | 25 ppm/K |
| Green | 5 | ×100,000 | ±0.5% | 20 ppm/K |
| Blue | 6 | ×1,000,000 | ±0.25% | 10 ppm/K |
| Violet | 7 | ×10,000,000 | ±0.1% | 5 ppm/K |
| Grey | 8 | ×100,000,000 | ±0.05% | 1 ppm/K |
| White | 9 | ×1,000,000,000 | – | – |
| Gold | – | ×0.1 | ±5% | – |
| Silver | – | ×0.01 | ±10% | – |
| Pink | – | ×0.001 | – | – |
| No band | – | – | ±20% | – |
How to read resistor bands
Hold the resistor so the tolerance band, usually gold, silver or brown with a slightly bigger gap, is on the right. Read the digit bands from the left, then the multiplier, which is the number of zeros to add or the power of ten to multiply by. On a 4 band resistor there are two digits; on 5 and 6 band resistors there are three. A sixth band gives the temperature coefficient: how much the value drifts per degree of temperature change.
If the result is not one of the standard preferred values, you may be reading it backwards. Resistors are made in E-series values: E12 has 12 values per decade (10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82), E24 has 24 and E96 has 96 for 1% parts. ResistorCode tells you which series a value belongs to. When in doubt, check with a multimeter.
LED resistors and power
The power a resistor must handle is the current squared times its resistance. Most small LED circuits dissipate well under 100 mW, so a common 1/4 W resistor is enough. Choose a rating at least twice the calculated power so it stays cool. Everything is calculated in your browser.
Frequently asked questions
What is a brown black red resistor?
1 kΩ: brown 1, black 0, red ×100.
What is red red brown?
220 Ω, a common LED resistor.
What if there is no fourth band?
A 3-band resistor has ±20% tolerance.
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