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Resistor Color Code Calculator: 4-Band and 5-Band
Pick the colors of each band to read the resistance and tolerance, or switch to the other mode and type a resistance to see which colors to look for. The result also shows the nearest standard E12 and E24 values.
How the color code works
Resistors are too small to print numbers on, so they carry colored bands. In a 4-band resistor the first two bands are significant digits, the third is a multiplier, and the fourth is the tolerance. A 5-band resistor adds a third digit for precision parts. The digit colors are black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, grey 8 and white 9.
The multiplier band gives the power of ten by which the digits are multiplied, using the same colors, plus gold for ×0.1 and silver for ×0.01. For example, yellow, violet, red is 4, 7 and ×100, which gives 4,700 ohms or 4.7 kΩ. Gold as the tolerance band means ±5 percent, so the real value of that part may lie anywhere from 4,465 to 4,935 ohms.
Standard E12 and E24 values
Resistors are not made in every value. The E series divide each decade logarithmically so that neighboring values are about the same percentage apart. The E12 series has 12 values per decade (1.0, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2) and suits 10 percent parts. The E24 series has 24 values per decade and suits 5 percent parts. The calculator picks the nearest value on a logarithmic scale, which is the fair way to measure closeness between ratios.
If your design asks for 5,000 ohms, the closest E24 part is 5.1 kΩ and the closest E12 part is 4.7 kΩ. Two resistors in series or parallel can get closer when precision matters.
Tips for reading real resistors
- Find the direction. The tolerance band is often gold or silver and sits slightly apart from the rest. A gold or silver first band is very unlikely.
- Watch similar colors. Red, orange and brown can look alike under poor light, as can grey and white. Confirm with a multimeter with the resistor out of circuit.
- Check the range. A measured value inside the tolerance range is a good part. Outside the range suggests heat damage or a misread.
- Remember power rating. The code gives resistance and tolerance only. Wattage is judged from the physical size or printed rating.
Limits and scope
This tool is for learning and for hobby and bench estimating. Some resistors also carry a temperature coefficient band, and surface-mount parts use printed codes instead of colors. Components used in mains-powered, medical or safety-critical equipment must be chosen against the datasheet and the rules for that equipment, and local codes and a qualified engineer decide what is acceptable. Do not rely on color alone when a wrong value could cause overheating or damage.
Worked example
A 4-band resistor striped yellow, violet, red, gold.
Inputs
| What do you want to do? | Read a 4-band resistor |
|---|---|
| Band 1 (first digit) | Yellow (4) |
| Band 2 (second digit) | Violet (7) |
| Multiplier band | Red (×100) |
| Tolerance band | Gold (±5%) |
Result
Bands: yellow, violet, red, gold
| Bands | yellow, violet, red, gold |
|---|---|
| Significant digits | 47 |
| Resistance | 4.7 kΩ |
| Tolerance | ±5% |
| Range | 4.465 kΩ to 4.935 kΩ |
| Nearest E12 value | 4.7 kΩ (exact) |
| Nearest E24 value | 4.7 kΩ (exact) |
- Read from the end with the bands grouped closer together; the tolerance band is usually set slightly apart.
Estimating note: Quantities and ratings here are estimates for planning and learning. Products, local codes and site conditions differ, so check manufacturer data and local regulations, and use a qualified professional for electrical, structural or safety-critical work.
Frequently asked questions
How do I read a 4-band resistor?
Read the first two bands as digits, apply the third band as a power-of-ten multiplier, and read the fourth band as tolerance. Yellow, violet, red, gold means 47 times 100, or 4.7 kΩ at ±5%.
What is the difference between 4-band and 5-band resistors?
A 5-band resistor has a third significant digit, so it can express more precise values, typically with tighter tolerances such as 1 percent, before the multiplier and tolerance bands.
What do gold and silver mean on a resistor?
As the multiplier, gold is ×0.1 and silver is ×0.01. As the tolerance band, gold is ±5 percent and silver is ±10 percent.
What are E12 and E24 values?
They are preferred-number series. E12 has 12 values per decade for 10 percent parts, and E24 has 24 values per decade for 5 percent parts, spaced logarithmically.
Which end do I start reading from?
Start from the end with the bands closer together, with the widely spaced tolerance band on the right. If unsure, a multimeter reading settles which direction gives the right value.
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References and sources
- IEC 60062: marking codes for resistors and capacitors. IEC 60063: preferred number series for resistors and capacitors.