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Resistor Color Code Calculator

Decode 4-, 5-, and 6-band resistors to a value, tolerance and tempco — or turn a value into its colour bands.

Decoder Reference

Direction
Bands
Resistance
4.7 kΩ
Tolerance
±5%

How Resistor Color Code Calculator works

Colour bands encode a resistor’s value because printing legible digits on a component a few millimetres long is impractical. The system is positional: the first bands are significant digits, the next is a decimal multiplier, and the last is the tolerance.

A four-band resistor gives two significant digits, a multiplier, and a tolerance — so brown-black-red-gold reads as 1, 0, ×100, ±5%, which is 1 kΩ. A five-band resistor adds a third significant digit for precision parts, and a six-band resistor adds a temperature coefficient in parts per million per degree Celsius.

Reading direction is the practical difficulty, since the bands are not always obviously oriented. The tolerance band is usually gold or silver and separated by a slightly wider gap, so it goes on the right. Where no gold or silver band exists — common on 1% parts, whose tolerance band is brown — the wider gap and the fact that a multiplier of black or brown is more plausible on the right both help.

Values are not arbitrary. They come from the E-series, a set of preferred values spaced logarithmically so that consecutive values differ by roughly the tolerance: E12 for 10% parts, E24 for 5%, E96 for 1%. That is why 4.7 kΩ exists and 5 kΩ generally does not.

Reference

  • Digits: black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, grey 8, white 9
  • Multiplier: as above as powers of ten; gold ×0.1, silver ×0.01
  • Tolerance: brown ±1%, red ±2%, green ±0.5%, blue ±0.25%, gold ±5%, silver ±10%, none ±20%
  • 4-band: digit digit multiplier tolerance
  • 5-band: digit digit digit multiplier tolerance 6-band: adds temperature coefficient

How to use this calculator

  1. Choose the band count

    Count the bands on the part — four for general purpose, five for precision, six when a tempco band is present.

  2. Orient the resistor

    Put the tolerance band on the right: it is usually gold or silver and set slightly apart from the others.

  3. Select each band colour

    Enter the colours left to right. The value, tolerance, and range appear immediately.

  4. Or work backwards

    Enter a resistance to see the band colours for it, along with the nearest standard E-series value.

Worked examples

A 1 kΩ 5% resistor

Given
Brown, black, red, gold
Result
1 kΩ ±5%, so 950 Ω to 1050 Ω

Brown-black is 10, red is ×100. One of the handful of codes worth memorising.

A 4.7 kΩ 1% resistor

Given
Yellow, violet, black, brown, brown
Result
4.7 kΩ ±1%

Five bands: 4, 7, 0 as digits then ×10. Note the third digit shifts the multiplier’s meaning versus a four-band part.

A sub-ohm resistor

Given
Orange, white, gold, gold
Result
3.9 Ω ±5%

A gold multiplier means ×0.1. Gold appearing in the third position is a multiplier, not a tolerance.

When to use it

  • Identifying an unlabelled resistor pulled from a parts drawer.
  • Verifying you fitted the right part before powering a board for the first time.
  • Finding the band colours for a value you need to pick out of a bin.
  • Checking whether a measured resistance is within the part’s marked tolerance.
  • Teaching or learning the colour code without a printed chart.

Things to watch out for

  • Always confirm with a multimeter when it matters. Faded, discoloured, or heat-damaged bands are easily misread, and red versus orange versus brown is genuinely hard under poor light.
  • Surface-mount resistors use numeric codes instead: three or four digits, or the EIA-96 system of two digits plus a letter.
  • Tolerance describes the manufacturing spread at reference temperature only. Temperature coefficient, ageing, and self-heating all shift the value further in service.
  • A resistor with no tolerance band is ±20%. These are rare in modern equipment and usually indicate an old part.

Frequently asked questions

How do I know which end to read from?

The tolerance band goes last. It is usually gold or silver and separated from the rest by a slightly wider gap. On 1% parts, where the tolerance band is brown, use the gap — and the fact that a multiplier band is more plausible next to it.

What is the difference between four and five bands?

Four bands give two significant digits plus a multiplier and tolerance; five bands give three significant digits, allowing values such as 4.99 kΩ. Five-band parts are typically 1% or better, which is why the extra digit is worth encoding.

What does the sixth band mean?

Temperature coefficient, in parts per million per degree Celsius. Brown is 100 ppm/°C, red 50, orange 15, yellow 25. It matters for precision analogue work where the resistor must hold its value across a temperature range.

Why is there no 5 kΩ resistor?

Because standard values follow the E-series, spaced logarithmically so consecutive values differ by roughly their tolerance. E24 goes 4.3, 4.7, 5.1 — 5.0 falls between two neighbours that already overlap it within tolerance, so it earns no place.

How do I read surface-mount resistors?

They use printed numbers, not colours. A three-digit code such as 472 means 47 × 10², or 4.7 kΩ. Four-digit codes add a significant figure. Precision parts use EIA-96: two digits index a value table and a letter gives the multiplier.

What tolerance does a resistor with no tolerance band have?

±20%. A four-band-looking resistor with only three coloured bands is an old ±20% part. Anything modern will carry at least a gold band for ±5%.

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