How to use the resistor calculator
- Choose the direction: Colors → value to decode a resistor, or Value → colors to find its bands.
- Choose how many bands the resistor has: 4, 5 or 6.
- For decoding, pick each band's color from left to right: the digit bands, then the multiplier.
- Pick the tolerance band, and on a 6-band resistor the temperature coefficient band.
- For the reverse, type the resistance and choose Ω, kΩ or MΩ. The answer shows the color names in order, and the table lists each band's meaning.
How the color code works
Each color stands for a number. The first two or three bands are digits, the next is a power of ten, and the rest give the precision:
The colors and values follow IEC 60062:2016, the international standard for resistor and capacitor marking:
| 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 | ×1,000 | ±0.05% | 15 ppm/K |
| Yellow | 4 | ×10,000 | ±0.02% | 25 ppm/K |
| Green | 5 | ×100,000 | ±0.5% | 20 ppm/K |
| Blue | 6 | ×1,000,000 | ±0.25% | 10 ppm/K |
| Violet | 7 | ×10,000,000 | ±0.1% | 5 ppm/K |
| Grey | 8 | ×100,000,000 | ±0.01% | 1 ppm/K |
| White | 9 | ×1,000,000,000 | – | – |
| Gold | – | ×0.1 | ±5% | – |
| Silver | – | ×0.01 | ±10% | – |
| Pink | – | ×0.001 | – | – |
| No band | – | – | ±20% | – |
Before the 2016 edition, grey usually meant ±0.05%, and some makers still print it that way, so check the datasheet for precision parts.
Worked example
The calculator starts with a 4-band resistor: yellow, violet, red, gold.
- Yellow = 4 and violet = 7, so the digits read 47
- Red multiplier = ×100, so R = 47 × 100 = 4,700 Ω = 4.7 kΩ
- Gold tolerance = ±5%, or ±235 Ω
- The real value can be anywhere from 4,465 Ω to 4,935 Ω
Switch to 5 bands and the black third band becomes a digit: 470 × 100 = 47 kΩ. Going the other way, a 220 Ω resistor needs red (2), red (2), brown (×10) and a tolerance band: red, red, brown, gold for ±5%.
Which end to start from
Hold the resistor so the bands bunched together are on the left. The tolerance band is often set apart, slightly wider, or gold or silver, and gold and silver never appear as the first band. If the reading gives a value that isn't a standard one, flip it and try again. Most common resistors come from the E12 and E24 series of preferred values (10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82 for E12, times a power of ten). The calculator tells you whether your value belongs to either series.
The temperature coefficient on a 6-band resistor says how much the value drifts with heat. At 100 ppm/K, a 100 Ω resistor changes by 0.01 Ω for each degree, or 0.5 Ω over a 50 °C rise. Once you know the resistance, the Ohm's law calculator gives the current and the power it must handle.
Frequently asked questions
What is the difference between 4-band and 5-band resistors?
A 4-band resistor has two significant digits, while a 5-band resistor has three, so it can mark values such as 4.75 kΩ. Five-band parts are usually precision resistors with ±1% or tighter tolerance. A 6-band resistor adds a temperature coefficient band.
What does a resistor with one black band mean?
It is a zero-ohm link: a piece of wire shaped like a resistor so machines can place it on a circuit board. It works as a jumper, and its resistance is a few milliohms.
Why does my multimeter read a different value?
The tolerance allows it. A 4.7 kΩ resistor at ±5% can measure anywhere from 4,465 Ω to 4,935 Ω. Measure with the resistor out of the circuit, since other parts in parallel lower the reading.
Can I find colors for any value?
A 4-band code shows two significant digits and a 5- or 6-band code shows three. If your value needs more, the calculator rounds it to the nearest one the bands can show and tells you so.
Related calculators
- Ohm's Law Calculator — Enter any two of voltage, current, resistance and power to get the other two, with the working shown.
- Voltage Drop Calculator — Voltage drop, percent drop and voltage at the load for copper or aluminum wire, AWG or mm², single- or three-phase.
- Electricity Cost Calculator — Energy use in kWh and running cost per day, month and year for any appliance, with typical wattages.
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