Resistor colour code calculator (4, 5 and 6 bands)
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Result
Decode the colour bands of a resistor or find the bands for a given resistance. Choose 4, 5 or 6 bands and the colours, and the calculator reads the digits and the multiplier, gives the resistance with its tolerance range and, for 6 bands, the temperature coefficient. It also tells you whether the value is a standard E12, E24, E48 or E96 value.
Step-by-step solution
Read the digit bands and the multiplier
Resistance
Tolerance range
Key formulas
- 4 bands
- R = (10·d₁ + d₂) × 10m, then the tolerance band
- 5 and 6 bands
- R = (100·d₁ + 10·d₂ + d₃) × 10m, then tolerance (and ppm/K)
- Digits
- black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, grey 8, white 9
- Multiplier
- gold ×0.1, silver ×0.01
How to read resistor colour codes
- Hold the resistor so the tolerance band, often gold or silver and set slightly apart, is on the right. Read the bands from left to right.
- The first two bands (three on a 5- or 6-band resistor) are digits: black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, grey 8, white 9.
- The next band is the multiplier, a power of ten with the same colour numbers: red means × 100. Gold means × 0.1 and silver × 0.01.
- The band after the multiplier is the tolerance: gold ±5%, silver ±10%, brown ±1%, red ±2%. A sixth band gives the temperature coefficient in ppm/K.
- Put it together: yellow, violet, red, gold is 47 × 100 Ω = 4.7 kΩ ± 5%, so the real value lies between 4.465 kΩ and 4.935 kΩ.
Questions and answers
Is there a way to remember the colour order?
The colours follow the rainbow from red to violet, with black and brown before it and grey and white after it: black, brown, red, orange, yellow, green, blue, violet, grey, white for 0 to 9. Many students use a mnemonic sentence whose words start with these letters.
Which end do I start reading from?
Start from the end with the band closest to the lead. The tolerance band is usually gold or silver and separated by a wider gap. A first band cannot be gold, silver or black, so if you read one of those first you are holding the resistor the wrong way round.
What is the difference between 4-band and 5-band resistors?
A 4-band resistor has two digit bands and is usually a ±5% or ±10% part. A 5-band resistor has three digit bands, so it can show values such as 4.75 kΩ, and is usually a precision part with ±1% or better. A 6-band resistor adds the temperature coefficient.
What are E-series values?
Resistors are made in preferred values so that the tolerance ranges of neighbouring values just overlap. E12 has 12 values per decade (10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82) for ±10% parts; E24 has 24 for ±5%, and E48 and E96 serve ±2% and ±1% resistors.
What does a zero-ohm resistor look like?
It has a single black band. It is used as a jumper wire that a placement machine can handle like a resistor.
Practise it yourself
Practise Series & parallel resistors
A calculator gives the answer. In the exam you need the method: practise it with new problems, hints and worked solutions.