OneTaskBy Tim King · Updated
Resistor Colour Code Calculator
4 and 5 Band Resistor Values
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How the Resistor Colour Code Calculator works
This resistor colour code calculator reads four- and five-band resistors. Choose whether the resistor has four or five bands, then pick the colour of each band from left to right. The result gives the resistance in ohms, kilohms or megohms, the tolerance, the range the real value can fall in, and whether the combination is a standard preferred value, which is a useful check that you read the bands the right way round. The colour code table sits below.
Resistor colour code calculator: digits, multiplier, tolerance
Through-hole resistors are too small to print a value on, so the value is coded as coloured bands. Each colour stands for a digit from 0 (black) to 9 (white), and the same colours also stand for powers of ten when used as the multiplier band. Reading the code is mechanical once you know the colours, but it is easy to read a resistor backwards or mistake red for orange under poor light, so a calculator that also reports whether the result is a standard value catches most slips.
Four-band resistors. The first two bands are the significant digits, the third is the multiplier and the fourth is the tolerance. Yellow, violet, red, gold reads 4, 7, ×100, ±5%: a 4.7 kΩ resistor that may actually measure anywhere from 4.465 to 4.935 kΩ. This is the common format for general-purpose 5 and 10 percent carbon film parts.
Five-band resistors. Precision resistors with 1 or 2 percent tolerance need three significant digits, so they carry three digit bands, then the multiplier, then the tolerance. Brown, black, black, red, brown is 1, 0, 0, ×100, ±1%: a 10 kΩ 1 percent part. Metal film resistors, the blue-bodied ones, are usually five-band.
Which way round. The tolerance band is usually gold or silver, colours that never appear as a digit, and it sits slightly apart from the others or nearer one end. Hold the resistor so that band is on the right. On five-band resistors with a brown tolerance band this is harder; if a reading gives an odd value such as 2.35 kΩ, try it the other way, and use the standard-value line in the result as a tie-breaker. Preferred values in the E24 series (1.0, 1.1, 1.2, 1.3, 1.5, 1.6, 1.8, 2.0, 2.2, 2.4, 2.7, 3.0, 3.3, 3.6, 3.9, 4.3, 4.7, 5.1, 5.6, 6.2, 6.8, 7.5, 8.2, 9.1 and their multiples of ten) cover almost every 5 percent resistor you will meet.
Gold and silver multipliers. A gold multiplier band means ×0.1 and silver ×0.01, so resistors under 10 Ω can be coded: red, red, gold, gold is 2.2 Ω ±5%. These low values turn up as current sense and fuse resistors.
Tolerance and what it means. A ±5% resistor marked 1 kΩ is guaranteed to be between 950 and 1,050 Ω; if the circuit needs closer than that, use a 1 percent part or measure and select. The result's range line shows the guaranteed spread for whatever tolerance you picked. Temperature coefficient, shown by a sixth band on some precision resistors, is not covered here.
Surface mount parts. SMD resistors use printed numeric codes instead of colours: three or four digits where the last is the multiplier, or the EIA-96 letter code. Those are a different system, though the digit-and-multiplier idea is the same.
E12 colour codes
Four-band resistors with a gold tolerance band.
Resistance and tolerance range for E12 colour codes
| Bands 1 to 3 | Resistance | Range |
|---|---|---|
| Brown, Black, Brown | 100 Ω ± 5% | 95 Ω to 105 Ω |
| Brown, Red, Brown | 120 Ω ± 5% | 114 Ω to 126 Ω |
| Brown, Green, Brown | 150 Ω ± 5% | 142.5 Ω to 157.5 Ω |
| Brown, Grey, Brown | 180 Ω ± 5% | 171 Ω to 189 Ω |
| Red, Red, Brown | 220 Ω ± 5% | 209 Ω to 231 Ω |
| Red, Violet, Brown | 270 Ω ± 5% | 256.5 Ω to 283.5 Ω |
| Orange, Orange, Brown | 330 Ω ± 5% | 313.5 Ω to 346.5 Ω |
| Orange, White, Brown | 390 Ω ± 5% | 370.5 Ω to 409.5 Ω |
| Yellow, Violet, Brown | 470 Ω ± 5% | 446.5 Ω to 493.5 Ω |
| Green, Blue, Brown | 560 Ω ± 5% | 532 Ω to 588 Ω |
| Blue, Grey, Brown | 680 Ω ± 5% | 646 Ω to 714 Ω |
| Grey, Red, Brown | 820 Ω ± 5% | 779 Ω to 861 Ω |
| Brown, Black, Red | 1 kΩ ± 5% | 950 Ω to 1.05 kΩ |
| Brown, Red, Red | 1.2 kΩ ± 5% | 1.14 kΩ to 1.26 kΩ |
| Brown, Green, Red | 1.5 kΩ ± 5% | 1.425 kΩ to 1.575 kΩ |
| Brown, Grey, Red | 1.8 kΩ ± 5% | 1.71 kΩ to 1.89 kΩ |
| Red, Red, Red | 2.2 kΩ ± 5% | 2.09 kΩ to 2.31 kΩ |
| Red, Violet, Red | 2.7 kΩ ± 5% | 2.565 kΩ to 2.835 kΩ |
| Orange, Orange, Red | 3.3 kΩ ± 5% | 3.135 kΩ to 3.465 kΩ |
| Orange, White, Red | 3.9 kΩ ± 5% | 3.705 kΩ to 4.095 kΩ |
| Yellow, Violet, Red | 4.7 kΩ ± 5% | 4.465 kΩ to 4.935 kΩ |
| Green, Blue, Red | 5.6 kΩ ± 5% | 5.32 kΩ to 5.88 kΩ |
| Blue, Grey, Red | 6.8 kΩ ± 5% | 6.46 kΩ to 7.14 kΩ |
| Grey, Red, Red | 8.2 kΩ ± 5% | 7.79 kΩ to 8.61 kΩ |
Resistor colour worked examples
The formula: resistance = significant digits × multiplier; range = resistance ± resistance × tolerance ÷ 100.
First example. Yellow, violet, red, gold reads 4, 7, × 100, ±5%: 4,700 Ω (4.7 kΩ), anywhere from 4.465 to 4.935 kΩ.
Second example. A five-band brown, black, black, brown, brown reads 1, 0, 0, × 10, ±1%: 1,000 Ω (1 kΩ), from 990 Ω to 1.01 kΩ.
How many bands to read as digits: two on a four-band resistor and three on a five-band one; the next band is always the multiplier.
FAQ
How do I read a 4-band resistor?
First two bands are digits, third is the multiplier, fourth is tolerance. Brown, black, red, gold is 1, 0, ×100 = 1,000 Ω, or 1 kΩ, at ±5%. Pick the four colours in the calculator and the result shows the value and range.
How do I read a 5-band resistor?
The first three bands are digits, the fourth is the multiplier and the fifth is tolerance. Yellow, violet, black, brown, brown is 4, 7, 0, ×10 = 4,700 Ω at ±1%. Choose 5 bands in the calculator so the third digit band is included.
Which end do I start from?
Start at the end farthest from the tolerance band, which is often gold or silver and set slightly apart. If the resulting value is not a standard one, the calculator flags it, and reading the bands in reverse order will usually give a sensible value.
What do gold and silver mean?
As the tolerance band, gold is ±5% and silver is ±10%. As the multiplier band, gold is ×0.1 and silver ×0.01, which is how values below 10 ohms are marked. The table below shows both uses.
What if there is no tolerance band?
Only three bands means the tolerance is ±20%, the loosest grade, common on very old components. Choose None as the tolerance and the range line shows the wide spread such a resistor may have.
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