3.9 Ω resistor colour code
Four bands: Orange · White · Gold · Gold. The first two give the digits, the third multiplies, the fourth states how far off the real part may be.
Nominal
3.9 Ω
3.9 ohms
Real range at ±5%
3.705 Ω – 4.095 Ω
A gold band allows this much drift.
Series
E12
Held in almost every parts drawer.
Band by band
| Band | Colour | Meaning |
|---|---|---|
| 1 | Orange | 1st digit — 3 |
| 2 | White | 2nd digit — 9 |
| 3 | Gold | Multiplier — ×0.1 |
| 4 | Gold | Tolerance — ±5% |
How much it can take
Current and dissipation across the resistor, and the package you need. The suggested rating keeps a factor of two in hand, which is what anyone building a board actually does.
| Across it | Current | Dissipated | Package to pick |
|---|---|---|---|
| 3.3 V | 846 mA | 2.79 W | no standard part — needs a power resistor or a heatsink |
| 5 V | 1.28 A | 6.41 W | no standard part — needs a power resistor or a heatsink |
| 12 V | 3.08 A | 36.9 W | no standard part — needs a power resistor or a heatsink |
| 24 V | 6.15 A | 148 W | no standard part — needs a power resistor or a heatsink |
What you can actually get
Parts made
131
130th most of 1,465 values
In stock
1,379
across 2 of them
Cheapest at 100
$0.0015
each
Tolerances sold
±0.1% to ±10%
6 grades in all
Packages: 0603, 0805, 1206, 1210, 0402, 2512, 2010, 1225. Ratings: 30mW to 10W.
What ten of them actually cost
The price everyone quotes is the reel price. If you want ten, you cannot buy the reel — and the real figure is usually several times higher per piece.
Ten pieces
$0.29
$0.029 each · Cut Tape (CT) · minimum order 1
The reel price
$0.00358
each, but only from 100,000 pieces up
Sitting in stock
422,192
across 2 part numbers
Per piece, ten costs 8.1× the reel price. That gap is why a handful of resistors never costs what the headline price suggests.
Stocked in ±5%, rated 1/10 W to 1/4 W.
Cheapest part you can buy ten of: ERJ-2GEJ3R9X by Panasonic Industry — see it at Digi-Key.
Assembly stock from the JLCPCB library, read 2026-09-24. Retail prices and stock from Digi-Key, read 2026-09-24. Prices move — check the product page before ordering. That is what a board house will place for you — not everything a distributor sells.
The same value, marked differently
Five bands
OrangeWhiteBlackSilverBrown
Three significant digits and a ±1% band.
Values that can overlap this one
At ±5% the tolerance bands of neighbouring values run into each other. A part sold as one of these could measure the same as a 3.9 Ω — which is why measuring beats reading when it matters.
- 3.6 Ω3.42 Ω–3.78 Ω
- 3.74 Ω3.7026 Ω–3.7774 Ω
- 3.83 Ω3.7917 Ω–3.8683 Ω
- 3.92 Ω3.8808 Ω–3.9592 Ω
- 4.02 Ω3.9798 Ω–4.0602 Ω
- 4.12 Ω4.0788 Ω–4.1612 Ω
- 4.3 Ω4.085 Ω–4.515 Ω
If you do not have one
Standard values that land within 1% of 3.9 Ω when combined.