Science & Units
Resistor Color Code Table
The colour code exists because resistors are small, cylindrical and printed on every side. A number stamped on a 6 mm body would be unreadable from most angles, so the industry settled on coloured bands that can be seen whichever way the part is rotated. The code is defined by IEC 60062 and has barely changed since the 1920s.
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Reading it is mechanical once the two roles of a band are separated. The first two bands of a four-band resistor are digits, the third is a multiplier expressed as ten to the power of its digit, and the fourth is tolerance. A five-band resistor adds a third digit before the multiplier, which is how 1% parts are distinguished from 5% parts that would otherwise look identical.
The trap is that the same colour means different things in different positions. Black is 0 as a digit and ×1 as a multiplier. Brown is 1 as a digit, ×10 as a multiplier and ±1% as a tolerance. Gold and silver break the pattern entirely: they are not digits at all, only multipliers (0.1 and 0.01) or tolerances (±5% and ±10%).
One practical note on direction. Bands are grouped at one end with a slightly larger gap before the tolerance band, so the tolerance band is the one standing apart. If the spacing is ambiguous, read from the end with the bands closest together — and if the reading gives a value that is not in the E12 or E24 series, you have probably started from the wrong end.
The ten digit colours
| Colour | Digit | Multiplier | Tolerance when last |
|---|---|---|---|
| Black | 0 | × 1 | — |
| Brown | 1 | × 10 | ±1% |
| Red | 2 | × 100 | ±2% |
| Orange | 3 | × 1,000 | — |
| Yellow | 4 | × 10,000 | — |
| Green | 5 | × 100,000 | ±0.5% |
| Blue | 6 | × 1,000,000 | ±0.25% |
| Violet | 7 | × 10,000,000 | ±0.1% |
| Grey | 8 | × 100,000,000 | ±0.05% |
| White | 9 | × 1,000,000,000 | — |
The multiplier is ten to the power of the digit, so the same colour carries two meanings depending on its position. Black as a digit is 0; black as a multiplier is ×1.
The three colours that are not digits
| Colour | Multiplier | Tolerance | Where it can appear |
|---|---|---|---|
| Gold | × 0.1 | ±5% | Multiplier or tolerance band |
| Silver | × 0.01 | ±10% | Multiplier or tolerance band |
| No band | — | ±20% | Tolerance position only |
Gold and silver never appear as a digit. A gold band in the multiplier position divides the value by ten, which is how sub-ohm values are marked.
Four-band resistors worked through
| Bands | Reading | Value |
|---|---|---|
| Brown, black, red, gold | 10 × 100 | 1 kΩ |
| Red, red, brown, gold | 22 × 10 | 220 Ω |
| Yellow, violet, orange, gold | 47 × 1,000 | 47 kΩ |
| Green, blue, red, gold | 56 × 100 | 5.6 kΩ |
| Orange, orange, yellow, gold | 33 × 10,000 | 330 kΩ |
| Brown, green, black, silver | 15 × 1 | 15 Ω |
Four-band: digit, digit, multiplier, tolerance. The tolerance band is usually gold or silver and sits slightly apart from the others.
Five-band resistors worked through
| Bands | Reading | Value |
|---|---|---|
| Brown, black, black, brown, brown | 100 × 10 | 1 kΩ |
| Brown, black, black, red, brown | 100 × 100 | 10 kΩ |
| Red, red, black, black, brown | 220 × 1 | 220 Ω |
| Yellow, violet, black, red, brown | 470 × 100 | 47 kΩ |
| Blue, grey, black, brown, brown | 680 × 10 | 6.8 kΩ |
Five-band: digit, digit, digit, multiplier, tolerance. Precision resistors use this layout, and the third digit is what distinguishes them from four-band parts.
How to Use These Tables
- Four-band part: read digit, digit, multiplier, tolerance. Brown-black-red-gold is 1, 0, ×100, ±5%, which is 1 kΩ.
- Five-band part: read digit, digit, digit, multiplier, tolerance. Brown-black-black-brown-brown is 1, 0, 0, ×10, ±1%, which is also 1 kΩ but to a tighter tolerance.
- Gold in the multiplier position divides by ten: brown-black-gold-gold is 1, 0, ×0.1, ±5%, or 1 Ω.
- Sanity check the result against the E12 series (10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82). A reading of 43 Ω means a band was misread.
- Measuring in circuit: a resistor reads lower than its marked value because parallel paths exist. Lift one leg before concluding the part has drifted.
Common Questions
Which end do I start reading from?
The end where the bands are closest together. The tolerance band sits slightly apart from the group, so it is always last. If the spacing is even, start from the end that gives a value in the standard E-series.
What does a gold band mean?
It depends on position. In the tolerance position it means ±5%. In the multiplier position it means ×0.1, which is how values below one ohm are marked. It is never a digit.
How do I tell a four-band from a five-band resistor?
Count the bands. Four bands are digit, digit, multiplier, tolerance; five bands add a third digit before the multiplier. Five-band parts are usually precision types at 1% or better.
What is the difference between a 1 kΩ 5% and a 1 kΩ 1% resistor?
Only the tolerance. The five-band version reads brown-black-black-brown-brown and the four-band reads brown-black-red-gold. The nominal value is identical; the guaranteed range is not.
Why does a resistor measure low in circuit?
Because other components are in parallel with it. A resistor in a live circuit sees every path around it. Desolder one leg, or at least lift it, before comparing the meter reading with the bands.
Are there colours that are never used?
All ten digit colours are used, but only brown, red, green, blue, violet, grey, gold and silver appear as tolerance bands. Orange, yellow, black and white have no tolerance meaning.
More Science & Units
Sources
- IEC 60062 — Marking codes for resistors and capacitors — International Electrotechnical Commission
- IEC 60063 — Preferred number series for resistors and capacitors — International Electrotechnical Commission
- NIST — Standard resistor calibration and colour code reference — National Institute of Standards and Technology
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