Through-hole resistors are too small to print a number on, so their value is painted as a sequence of colored bands. This calculator reads that code in either direction: pick the colors you see to get the resistance, tolerance range and temperature coefficient, or enter a resistance to find the bands to look for in a parts drawer. The diagram redraws the resistor with your bands so you can compare it with the part in your hand.
How to use the resistor color code calculator
- Choose Read the colors to decode a resistor, or Find colors for a value to go the other way.
- Select 4 bands, 5 bands or 6 bands to match the resistor.
- When reading, pick the color of each digit band, then the multiplier and tolerance bands. On a 6-band resistor, also pick the temperature coefficient band.
- When encoding, type the resistance and choose Ω, kΩ, MΩ or GΩ, plus the tolerance you want.
- Read the value, its minimum and maximum, and whether it belongs to a standard E-series. The table lists what each band means.
The color code chart
The code is defined by the international standard IEC 60062. Each color stands for a digit, a power of ten and, on some bands, a tolerance or temperature coefficient.
| Color | Digit | Multiplier | Tolerance | Temp. coefficient |
|---|---|---|---|---|
| Black | 0 | ×1 | — | 250 ppm/K |
| Brown | 1 | ×10 | ±1% | 100 ppm/K |
| Red | 2 | ×100 | ±2% | 50 ppm/K |
| Orange | 3 | ×1k | ±0.05% | 15 ppm/K |
| Yellow | 4 | ×10k | ±0.02% | 25 ppm/K |
| Green | 5 | ×100k | ±0.5% | 20 ppm/K |
| Blue | 6 | ×1M | ±0.25% | 10 ppm/K |
| Violet | 7 | ×10M | ±0.1% | 5 ppm/K |
| Grey | 8 | ×100M | ±0.01% | 1 ppm/K |
| White | 9 | ×1G | — | — |
| Gold | — | ×0.1 | ±5% | — |
| Silver | — | ×0.01 | ±10% | — |
| None | — | — | ±20% | — |
Older charts sometimes list orange and yellow tolerances as ±3% and ±4%; those are obsolete, and you will rarely meet a resistor that uses them.
Worked examples
Yellow, violet, red, gold (4 bands, the default)
Digits 4 and 7 make 47. Red multiplies by 100, so R = 47 × 100 = 4.7 kΩ.
Gold is ±5%: 4,700 × 0.95 = 4,465 Ω and 4,700 × 1.05 = 4,935 Ω. The value appears in the E6, E12 and E24 series.
A precision 5-band part. Brown, black, black, red, brown reads 1, 0, 0 → 100, times 100 = 10 kΩ, and the brown tolerance band makes it ±1% (9.9 kΩ to 10.1 kΩ).
Finding the bands for 220 Ω. Write 220 as two digits times a power of ten: 22 × 10¹. The bands are red, red, brown, then gold for ±5%. Values under 10 Ω use gold or silver as the multiplier, so 0.47 Ω becomes yellow, violet, silver.
Tips for reading real resistors
- Find the tolerance band first. It is usually gold, silver or brown, and often has a wider gap before it. Read from the other end.
- Check the body color. Beige bodies are typically 4-band carbon-film parts; blue or green bodies are usually 5-band metal-film parts.
- Confirm with a meter. Brown, red and orange fade toward one another on old or overheated parts. Measure with a multimeter out of circuit if the value matters.
- Watch for 0 Ω links. A single black band marks a zero-ohm jumper, not a resistor.
Preferred values
Manufacturers do not make every value. They follow the IEC 60063 E-series, where each step is a fixed percentage above the last, so the tolerance bands of neighboring values just meet. The E12 series (±10%) has 12 values per decade, E24 (±5%) has 24 and E96 (±1%) has 96. If the calculator reports that your value is not standard, use the suggested E24 value or combine parts with the series and parallel resistor calculator.
Once you know the value, the Ohm’s law calculator gives the current and power for a given voltage, and the LED resistor calculator picks a standard value for an LED.
These values are for identifying components in low-voltage electronics. For anything connected to mains power, follow your local electrical code and use a licensed electrician.
Frequently asked questions
How do I read a 4-band resistor?
Hold the resistor so the tolerance band, usually gold or silver, is on the right. The first two bands are digits, the third is the power of ten to multiply by, and the fourth is the tolerance. Yellow, violet, red, gold reads 4, 7, ×100, ±5%, so the resistor is 4.7 kΩ.
Which end of a resistor do I start reading from?
Start from the end with the band closest to the lead. The tolerance band is often set slightly apart from the others, and gold or silver never appears as the first band. If the first band you read is black, you are probably reading backwards.
What is the difference between 4-band, 5-band and 6-band resistors?
A 4-band resistor shows two significant digits, which suits 5% and 10% parts. A 5-band resistor adds a third digit for precision values such as 1% parts. A 6-band resistor adds a final band for the temperature coefficient, in parts per million per kelvin.
What does the tolerance band mean?
It is the allowed deviation from the marked value. A 4.7 kΩ resistor with a gold (±5%) band may measure anywhere from 4.465 kΩ to 4.935 kΩ and still be within specification.
Why can't I find my value in the color code?
Colors can only show two or three significant digits. Values such as 12.34 kΩ are rounded, and manufacturers usually stock only the preferred values of the IEC 60063 E-series, such as 4.7, 5.1 or 5.6 in each decade. The calculator tells you whether a value is standard and suggests the nearest E24 value.