How to read a resistor color code
Hold the resistor with the tolerance band (usually gold or silver, and slightly separated from the others) on the right and read from left to right:
- 4 bands: two digits, multiplier and tolerance. Typical of 5% carbon film resistors.
- 5 bands: three digits, multiplier and tolerance. Used on precision metal film resistors (1% or better).
- 6 bands: like 5 bands plus a final band for the temperature coefficient.
| Color | 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 k | — | 15 ppm/K |
| Yellow | 4 | ×10 k | — | 25 ppm/K |
| Green | 5 | ×100 k | ±0.5% | 20 ppm/K |
| Blue | 6 | ×1 M | ±0.25% | 10 ppm/K |
| Violet | 7 | ×10 M | ±0.1% | 5 ppm/K |
| Grey | 8 | ×100 M | ±0.05% | 1 ppm/K |
| White | 9 | ×1 G | — | — |
| Gold | — | ×0.1 | ±5% | — |
| Silver | — | ×0.01 | ±10% | — |
A classic mnemonic for the order 0 to 9 is "Bad Beer Rots Our Young Guts But Vodka Goes Well" (black, brown, red, orange, yellow, green, blue, violet, grey, white).
Example · yellow, violet, red, gold
Digits 4 and 7 → 47; red multiplier, ×100 → 4,700 Ω = 4.7 kΩ ±5%. The actual value can be anywhere between 4,465 Ω and 4,935 Ω.
Example · brown, black, black, red, brown
Digits 1, 0, 0 → 100; multiplier ×100 → 10,000 Ω = 10 kΩ ±1%.
Standard resistor values (E series)
Resistors are not made in every possible value. The E12, E24 and E96 series split each decade into 12, 24 or 96 logarithmically spaced values so that, with their tolerance, they cover the whole range with no gaps. That is why 4.7 kΩ exists but 5 kΩ does not. If you calculate a value for a circuit, the "Value → colors" tab gives you the nearest standard value in each series.
Frequently asked questions
Which end do I start reading from?
The tolerance band is usually set apart from the others and is almost never gold or silver in first place, because those colors have no digit. If in doubt, measure with a multimeter: of the two possible readings only one will be a standard value.
What does the temperature coefficient mean?
How much the resistance changes with temperature, in parts per million per kelvin. A 10 kΩ resistor at 100 ppm/K changes by 1 Ω per degree, i.e. 50 Ω if it heats up by 50 °C.
What about SMD resistors?
They use a numeric code instead of colors: in the 3-digit code the first two digits are the value and the third is the number of zeros (472 = 4.7 kΩ). An R marks the decimal point (4R7 = 4.7 Ω).