Free Online Resistor Color Code Decoder
Decode 4, 5, and 6-band resistor values and tolerances.
Four-band resistors use two digits, a multiplier and a tolerance. Five-band resistors add a third digit; six-band resistors add a temperature coefficient.
Reverse lookup snaps to the nearest E24 preferred value.
Decoding steps
- Choose the bands to see the calculation.
About the Resistor Color Code Decoder
Through-hole resistors are marked with colored bands instead of printed numbers. Each color maps to a digit, multiplier, tolerance or temperature coefficient, and reading the bands in the correct order reveals the component's value. This decoder supports four, five and six-band resistors, shows the resistance with a sensible prefix, and draws the selected bands on a resistor body. It also offers a reverse lookup that turns a target value into the nearest standard color combination.
Four, five and six bands
A four-band resistor uses two significant digits, a multiplier and a tolerance. Brown, black, red and gold means 1, 0, ×100 and ±5%, or 1 kΩ. A five-band resistor adds a third significant digit, allowing tighter values: the first three bands are digits, the fourth is the multiplier and the fifth is tolerance. A six-band resistor adds a temperature coefficient band, usually expressed in parts per million per kelvin. The extra digit explains why five-band parts can represent values such as 4.70 kΩ rather than only 4.7 kΩ.
How to read the bands
Start from the end opposite the tolerance band, which is usually separated by a slightly larger gap or is metallic. The first band is the most significant digit, the next band is the second digit, and so on. The multiplier band tells you how many zeros to append in decimal terms, or equivalently the power of ten. Gold and silver multipliers are 0.1 and 0.01, used for low-ohm values. The tolerance band tells you how far the actual resistance may drift from the nominal value: gold is ±5%, silver ±10%, brown ±1%, red ±2%.
E-series and preferred values
Resistors are manufactured in standard value series, not arbitrary numbers. E12 has 12 values per decade, E24 has 24, E48 has 48 and E96 has 96. Higher series allow tighter tolerances and more choices. A 5% resistor is normally an E24 part, while 1% parts are often E96. The reverse lookup in this tool snaps your target to the nearest E24 value, so entering 4.6 kΩ may return the standard 4.7 kΩ colors. That is a feature, not an error: the nearest purchasable value is usually what you want.
Temperature coefficient
The sixth band specifies how much the resistance changes with temperature, in ppm/K. Brown is 100 ppm/K, red 50, orange 15, yellow 25, blue 10 and violet 5. A 100 ppm/K resistor changes by 0.01% per kelvin, which matters in precision analog circuits but is negligible in many hobby projects. If the sixth band is absent, the part does not specify a coefficient in the color code, and the decoder reports a dash.
Practical checks
Lighting, paint wear and color blindness can make bands hard to distinguish, especially brown versus red or orange versus yellow. Measure the resistor with a multimeter before trusting a doubtful reading; the meter is the final authority. Also remember that the measured value may differ slightly from nominal because of tolerance and temperature. When decoding, confirm the band count and read from the correct end. The visual preview helps you compare the order you selected with the physical part in your hand.
Frequently asked questions
Which end do I start from?
Start at the end opposite the tolerance band. The tolerance band is often gold, silver or separated by a slightly wider gap. If the resistor has five or six bands, the same rule applies: digits first, then multiplier, tolerance and temperature coefficient.
Why does the reverse lookup not return my exact value?
It snaps to the nearest E24 preferred value because resistors are sold in standard series. Enter a value close to a standard number, or use the band selectors directly if you need an unconventional combination.
What is the difference between 4-band and 5-band 1% resistors?
A 4-band 1% resistor can only show two significant digits, so its value is limited to the E24-style grid. A 5-band 1% resistor shows three digits, matching E96 values such as 1.02 kΩ or 4.75 kΩ. Both are valid; the extra band improves resolution.