Resistor Color Code Calculator
Pick the colour of each band to read a resistor's resistance, tolerance and temperature coefficient, or type a resistance and get the bands to look for. A third mode rounds any calculated value to the nearest standard E-series resistor. Every result is drawn as a resistor and explained band by band, following IEC 60062. Free, no sign-up.
Read from the end that has the tolerance band (gold, silver or the widely spaced one). Gold and silver never appear as digits.
Results
4.7 kΩ
Resistance
±5%
Tolerance
4.465 kΩ – 4.935 kΩ
Actual value lies between
E6, E12, E24, E192
Standard series
The working
- 47 × 100 = 4,700 Ω
Band by band
| Band | Colour | Means |
|---|---|---|
| 1st digit | Yellow | Digit 4 |
| 2nd digit | Violet | Digit 7 |
| Multiplier | Red | × 100 |
| Tolerance | Gold | ±5% |
How to Use the Resistor Color Code Calculator
- 1. Choose a mode. Read the bands turns colours into a value, Find the bands for a value does the reverse, and Nearest standard value rounds a calculated resistance to a part you can buy.
- 2. Set the number of bands. Four bands carry two digits, five carry three, and six add a temperature coefficient. Count the bands on the part first.
- 3. Enter the colours or the value. Each menu shows what the colour means in that position, so you can see that red is 2 as a digit, ×100 as a multiplier and ±2% as a tolerance.
- 4. Read the drawing and the table. The resistor is drawn with its bands, followed by the value, the range the real resistance can lie in, and a band-by-band table of the working.
How the Colour Code Works
The colour code is defined in IEC 60062 (edition of 2016), the international standard for marking codes on resistors and capacitors. The same ten colours stand for the digits 0 to 9: black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, grey 8 and white 9. Gold and silver are added for the multiplier (×0.1 and ×0.01) and the tolerance (±5% and ±10%), and they never appear as digits.
| Bands | 1st–2nd (or 3rd) bands | Next band | Tolerance band | Sixth band |
|---|---|---|---|---|
| 4 bands | Two digits | Multiplier | Tolerance | — |
| 5 bands | Three digits | Multiplier | Tolerance | — |
| 6 bands | Three digits | Multiplier | Tolerance | Temperature coefficient (ppm/K) |
The tolerance colours are brown ±1%, red ±2%, green ±0.5%, blue ±0.25%, violet ±0.1%, grey ±0.05%, gold ±5% and silver ±10%; a resistor with no tolerance band is ±20%. For the sixth band, black means 250 ppm/K, brown 100, red 50, orange 15, yellow 25, green 20, blue 10, violet 5 and grey 1. A coefficient of 50 ppm/K means the resistance moves by about 0.5% over a 100 K temperature change.
Worked Examples
- Yellow, violet, red, gold (the calculator's starting point): digits 4 and 7, multiplier ×100, so 47 × 100 = 4,700 Ω = 4.7 kΩ ±5%. The real resistance lies between 4.465 kΩ and 4.935 kΩ.
- Brown, black, black, red, brown (five bands): digits 1, 0, 0, multiplier ×100, so 100 × 100 = 10 kΩ ±1%, between 9.9 kΩ and 10.1 kΩ.
- Brown, black, black, orange, brown, red (six bands): 100 × 1,000 = 100 kΩ ±1%, with a coefficient of 50 ppm/K.
- Yellow, violet, silver, silver: 47 × 0.01 = 0.47 Ω ±10%, a typical current-sense resistor.
Standard Values: the E-Series
Resistors are not sold in every value. IEC 60063 defines preferred-number series in which each step is a roughly constant ratio, so neighbouring values just overlap when you allow for tolerance. Choosing a ±5% resistor from the E24 series means any resistance you need is within about 5% of a stocked part.
| Series | Values per decade | Usual tolerance | Digits on the part |
|---|---|---|---|
| E6 | 6 | ±20% | 2 |
| E12 | 12 | ±10% | 2 |
| E24 | 24 | ±5% | 2 |
| E48 | 48 | ±2% | 3 |
| E96 | 96 | ±1% | 3 |
| E192 | 192 | ±0.5% and tighter | 3 |
To choose a part for a calculated 4,800 Ω, set the mode to Nearest standard value. In E24 or E12 the nearest value is 4.7 kΩ, 2.08% below what you asked for; in E96 it is 4.75 kΩ, only 1.04% below. The tool also shows the next value up and down, because the better choice is not always the nearest: a current-limiting resistor, for instance, should usually err on the high side.
Which end do you read from?
Start at the end that is farthest from the tolerance band. The tolerance band is usually gold or silver, and it often sits slightly apart from the others. If you cannot tell, decode both directions: usually only one reading gives a standard E-series value. When in doubt, or when the colours are faded or look alike, measure the resistance with a multimeter with the resistor out of the circuit.
Frequently Asked Questions
- How do I read a 4-band resistor?
- The first two bands are digits, the third is the multiplier, and the fourth is the tolerance. Yellow, violet, red, gold is 4, 7, ×100, ±5%, which is 4,700 Ω or 4.7 kΩ ±5%. If there is no fourth band, the resistor is ±20%.
- What is the difference between 4-band, 5-band and 6-band resistors?
- A 4-band resistor has two significant digits, a 5-band has three, so it can show precision values such as 4.75 kΩ, and a 6-band adds a temperature coefficient in ppm/K. Five- and six-band parts are normally 1% or better.
- What does a gold or silver band mean?
- In the multiplier position, gold means ×0.1 and silver ×0.01. In the tolerance position, gold means ±5% and silver ±10%. Gold and silver are never digits, so a gold or silver band is always a multiplier or a tolerance.
- What is the temperature coefficient band?
- On a 6-band resistor, the sixth band gives how far the resistance drifts per kelvin, in parts per million: brown is 100 ppm/K, red 50, orange 15. A 100 ppm/K part changes by 0.1% over a 10 K change and 1% over 100 K.
- What are E12, E24 and E96 values?
- They are the standard series of preferred resistances from IEC 60063, with 12, 24 and 96 values in each decade (1.0 to 9.99 and so on). E12 parts are usually ±10%, E24 ±5% and E96 ±1%. A value such as 4.7 kΩ is in E6, E12 and E24 (and E192); 4.75 kΩ is in E96.
- Why does the calculator say my value needs 5 bands?
- Four bands hold only two significant digits, so 4,750 Ω cannot be written on them without changing it to 4,700 or 4,800 Ω. Switch to 5 bands for three digits, or use the nearest-value mode to pick a part that four bands can show.