390 Ω resistor colour code
orangewhitebrowngold
390 Ω ±5%
orange white brown gold — four bands, read from the end with the bands closest to it.
| Band 1 — first digit | orange = 3 |
| Band 2 — second digit | white = 9 |
| Band 3 — multiplier | brown × 10 |
| Band 4 — tolerance | gold ± 5% |
| Value | 390 Ω |
| Acceptable range | 370.5 Ω to 409.5 Ω |
Reading it
The two digit bands give 39 and the multiplier band multiplies it by 10:
39 × 10 = 390 Ω
Which end to start from is the part that catches people. The tolerance band is the one set slightly apart from the other three, and it is gold or silver far more often than not — neither of which is a digit colour, so a gold or silver band tells you which end you are at. Read from the opposite end.
What ±5% actually means
A 390 Ω ±5% resistor is in specification anywhere from 370.5 Ω to 409.5 Ω. A meter reading of 370.5 Ω on this part is not a fault and not a reason to replace it.
390 Ω is one of the E24 values — the 24 steps per decade that ±5% resistors are made in. The steps are spaced so that the tolerance bands of neighbouring values just about touch: there is no gap between one value's range and the next, and no point making anything in between. It is the same reasoning that gives ±10% parts only 12 values per decade.
The same resistor with five bands
Precision resistors carry five bands: three digits, a multiplier and a tighter tolerance. The same 390 Ω reads
orangewhiteblackblackbrown
— orange white black black brown. The digits become 3, 9 and 0, and the multiplier drops one decade to black to compensate. The brown final band is ±1% rather than ±5%, which narrows the range to 386.1 Ω–393.9 Ω.
How much this one can take
A resistor's limit is heat, not voltage or current on their own: the power it turns into heat is V² ÷ R, so the same wattage allows very different numbers at 390 Ω than it does at a value ten times away. This is the part of a colour code lookup people actually came for and charts leave out.
| Rating | Maximum current | Maximum voltage |
|---|---|---|
| ⅛ W | 17.9 mA | 7 V |
| ¼ W | 25.3 mA | 9.9 V |
| ½ W | 35.8 mA | 14 V |
| 1 W | 50.6 mA | 19.7 V |
The quarter-watt part is the one in everybody's drawer: at 390 Ω it will carry 25.3 mA or stand 9.9 V across it, and not both at once — those are the same limit expressed two ways.
390 Ω is a ±10% value too
390 Ω is one of the twelve E12 values as well as one of the twenty-four E24 ones, which means it is made at ±10% and ±5% both. In practice that makes it easier to find and cheaper: E12 values are what a beginner's assortment box contains, and a shop that stocks one range stocks this value.
The nearest E12 value is 390 Ω — this one.
The same resistor as a surface-mount marking
Surface-mount resistors have no room for bands, so they carry printed digits instead — and 391 is what 390 Ω looks like on one. The scheme is the colour code with the colours replaced by the digits they stood for: two significant figures and a count of zeros.
| Marking | Used on | Reads as |
|---|---|---|
391 | Three-digit, ±5% parts | 39 followed by one zero |
3900 | Four-digit, ±1% parts | 390 with no zeros after it |
A four-digit marking is not a different system, only a more precise one: it carries three significant figures instead of two and takes one off the zero count, which is why 391 and 3900 are the same 390 Ω. If a board has both on it, the four-digit parts are the ±1% ones.
Very small ±1% parts use a third scheme, EIA-96, where two digits index a table of values and a letter gives the multiplier — 01C rather than 1002. It only covers the E96 series, so it has no marking for most of the E24 values on this site, and a marking with a letter in the middle is never one of these codes.
Where 390 Ω turns up
Hundreds of ohms is the classic LED resistor range on a 5 V rail, and the usual value for series protection on an input pin. It is the most-reached-for decade in hobby electronics after the kilohms.
Frequently asked questions
What is the colour code for a 390 Ω resistor?
orange white brown gold on a four-band resistor: orange for 3, white for 9, brown for a multiplier of ×10, and gold for ±5%.
What resistor is orange white brown gold?
390 Ω, ±5%. The first two bands are the digits 3 and 9, the third multiplies by 10, and the gold band is the tolerance.
What is the tolerance range of a 390 Ω ±5% resistor?
370.5 Ω to 409.5 Ω. A resistor measuring anywhere in that range is within specification, which is why a meter reading of 370.5 Ω on a 390 Ω part is not a fault.
What is the five-band code for 390 Ω?
orange white black black brown — three digit bands (3, 9, 0), then black as the multiplier and brown for ±1%. Five-band resistors carry an extra significant figure, so the third digit is the zero that a four-band code leaves to the multiplier.
Nearby values
- 430 Ω resistor colour code — yellow orange brown gold
- 470 Ω resistor colour code — yellow violet brown gold
- 510 Ω resistor colour code — green brown brown gold
- 560 Ω resistor colour code — green blue brown gold
- 620 Ω resistor colour code — blue red brown gold
- 680 Ω resistor colour code — blue grey brown gold
- 750 Ω resistor colour code — violet green brown gold
- 820 Ω resistor colour code — grey red brown gold
- 910 Ω resistor colour code — white brown brown gold
- 1 kΩ resistor colour code — brown black red gold