Resistor Color Code
Pick the colors on a 4-band or 5-band resistor and read off its resistance and tolerance.
Exact value: 1,000 Ω. The tolerance band sets the guaranteed range.
A resistor with bands brown · black · red · gold reads 1 kΩ ±5%. The first two bands are the digits 1 and 0, giving 10; the red multiplier means ×100, so 10 × 100 = 1000 Ω = 1 kΩ. Gold sets the tolerance at ±5%, a 950–1050 Ω range.
How the resistor color code works
Through-hole resistors are too small to print numbers on, so their value is painted in colored rings. Each color maps to a digit (0–9) under the IEC 60062 standard. On a 4-band resistor the first two bands are significant digits, the third is a power-of-ten multiplier, and the fourth is the tolerance. A 5-band resistor (used for precision parts) adds a third significant digit, shifting the multiplier and tolerance one band to the right.
Read the bands from the end where they are grouped together; the lone tolerance band — usually gold or silver — sits nearest the opposite end. Once you have the value, you can feed it into Ohm’s law or combine it with others in series and parallel.
4-band: R = (d₁d₂) × multiplier. 5-band: R = (d₁d₂d₃) × multiplier. The final band gives the ± tolerance.
Worked example
Decode a 4-band resistor banded brown · black · red · gold:
- 1 Orient the resistor. Put the grouped bands on the left and the lone tolerance band (gold or silver) on the right, then read left to right.
- 2 Read the digit bands. Brown = 1 and black = 0, so the significant digits are 1 and 0 — the number 10.
- 3 Apply the multiplier. The red band is the multiplier ×100, so 10 × 100 = 1000 Ω.
- 4 Convert to a prefix. 1000 Ω = 1 kΩ (divide by 1000 for kΩ, by 1,000,000 for MΩ).
- 5 Read the tolerance. Gold means ±5%, so the true value lies between 950 Ω and 1050 Ω.
IEC 60062 resistor color code
Digit and multiplier apply to the value bands; tolerance applies only to the final band. A blank cell means that color is not used for that role.
| Color | Digit | Multiplier | Tolerance |
|---|---|---|---|
| Black | 0 | ×1 | — |
| Brown | 1 | ×10 | ±1% |
| Red | 2 | ×100 | ±2% |
| Orange | 3 | ×1k | — |
| Yellow | 4 | ×10k | — |
| Green | 5 | ×100k | ±0.5% |
| Blue | 6 | ×1M | ±0.25% |
| Violet | 7 | ×10M | ±0.1% |
| Grey | 8 | ×100M | ±0.05% |
| White | 9 | ×1G | — |
| Gold | — | ×0.1 | ±5% |
| Silver | — | ×0.01 | ±10% |
4-band vs 5-band, and what tolerance means
The extra digit on a 5-band resistor lets manufacturers print finer values — for example 4 · 7 · 5 with a ×10 multiplier gives 4.75 kΩ, which a 4-band part cannot express. The tolerance band tells you how far the real resistance may stray from the printed value: a ±5% 1 kΩ resistor is guaranteed only to fall between 950 Ω and 1050 Ω. Tighter tolerances (±1%, ±0.1%) cost more and almost always appear on 5-band parts. Gold and silver are the giveaway that you are looking at the tolerance end, since neither color is ever a significant digit.