Resistor Color Code Calculator (4, 5 & 6 Band)
Decode any resistor by its color bands, or work backwards from a value. Choose 4, 5 or 6 bands to get the resistance in ohms, the tolerance and (for 6 band parts) the temperature coefficient, plus the allowed range. Reverse mode finds the nearest preferred value and the exact band colors for a target resistance.
Formula
Worked example
A 5 band resistor Brown, Black, Black, Brown, Brown: digits 1, 0, 0 make 100, the brown multiplier is ×10, so R = 100 × 10 = 1,000 Ω = 1 kΩ. The brown tolerance band gives ±1%, allowing 990 Ω to 1,010 Ω. In reverse, asking for 4,700 Ω in the E24 series returns 4.7 kΩ: Yellow, Violet, Red (mult.), Gold (tol.).
How the bands encode a value (4, 5 and 6 band)
A resistor packs its resistance into colored bands. On a 4 band part the first two bands are significant digits, the third is a multiplier (a power of ten), and the fourth is the tolerance. On a 5 band part there are three digit bands before the multiplier, which lets the value carry an extra significant figure for precision parts. A 6 band resistor adds one more band on the end: the temperature coefficient, measured in parts per million per kelvin (ppm/K), which says how much the resistance shifts as the part heats up. This calculator switches between all three layouts so you read whatever is in front of you.
Reading the bands in the right order
Orientation matters because the code is not symmetrical. Hold the resistor so the grouped bands are on the left and the lone tolerance band (commonly gold or silver) is on the right, then read left to right. If you read a 1 kΩ resistor backwards you might mistake it for a far larger value, so always start from the digit end. When a resistor has no tolerance band at all, it carries a default tolerance of ±20%, the loosest grade still found on older or low precision parts.
Reverse mode: from a value to the bands
Sometimes you know the resistance you want and need the color bands or the nearest part you can actually buy. Switch to reverse mode, type a target resistance, and pick a preferred value series. Resistors are mass produced to standardized E-series values rather than arbitrary numbers, which is why you see 4.7 kΩ and 6.8 kΩ but rarely 5 kΩ. The calculator finds the closest standard value in your chosen series (E6, E12, E24 or the 1% E96 set), reports how far it sits from your target, and prints the exact band colors that encode it. If the gap is too large, combine two resistors in series or parallel, or step up to a tighter series.
Tolerance, temperature coefficient and drift
The tolerance band states the manufacturer guarantee: a ±5% gold band on a 1 kΩ part means the actual resistance lies between 950 Ω and 1,050 Ω. Tighter tolerances such as ±1% (brown) cost more and are used where precise voltage dividers, timing circuits or sensor front ends demand it. On 6 band resistors the temperature coefficient adds a second source of error: at 100 ppm/K a 10 kΩ resistor shifts by 1 Ω for every degree of heating, so a 50 °C rise moves it by about 50 Ω. Enter a temperature rise and the calculator estimates that drift, which matters in precision analog work where the part runs warm.
Resistor color code reference
| Color | Digit | Multiplier | Tolerance | Temp. coeff. |
|---|---|---|---|---|
| Black | 0 | ×1 | , | 250 ppm/K |
| Brown | 1 | ×10 | ±1% | 100 ppm/K |
| Red | 2 | ×100 | ±2% | 50 ppm/K |
| Orange | 3 | ×1k | , | 15 ppm/K |
| Yellow | 4 | ×10k | , | 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 | ±0.05% | 1 ppm/K |
| White | 9 | ×1G | , | , |
| Gold | , | ×0.1 | ±5% | , |
| Silver | , | ×0.01 | ±10% | , |
Each color carries a digit, a multiplier, a tolerance and a temperature coefficient (6 band only).
Frequently asked questions
How do I read a 4, 5 or 6 band resistor color code?
Read from the end where the bands are bunched together. On a 4 band part the first two bands are digits, then a multiplier, then tolerance. A 5 band part has three digit bands before the multiplier. A 6 band part adds a temperature coefficient band on the far end. Multiply the digit number by the multiplier to get the resistance in ohms.
How do I find the color bands for a resistance I want?
Switch to reverse mode, enter the target resistance, and choose a preferred value series (E6, E12, E24 or E96). The calculator finds the nearest standard value you can actually buy, shows how far it is from your target, and prints the exact band colors that encode it. For a value between standards, combine two resistors or pick a tighter series.
What does the temperature coefficient band mean?
On 6 band resistors the last band gives the temperature coefficient in parts per million per kelvin (ppm/K). At 100 ppm/K a resistor changes by 0.01% for every degree it heats up. Enter a temperature rise and the calculator estimates the resulting drift in ohms, which matters for precision and warm-running circuits.
What does the tolerance band mean?
It states how far the real resistance may differ from the printed value. A gold band is ±5% and silver is ±10%, while brown (±1%) and red (±2%) mark precision parts. A 1 kΩ resistor at ±5% can legitimately measure anywhere from 950 Ω to 1,050 Ω.