Electronics visual tool
Decode or Build Any Resistor Color Code
Decode 3-, 4-, 5- or 6-band resistors, or enter an ohmic value and build the correct bands. The oversized resistor drawing labels every band so a 100-ohm, 100-kilohm or custom resistor can be understood at a glance.
Choose how you want to calculate
Selection and purchasing details
The wattage changes the physical size and power handling of a resistor, not the color bands for its resistance value.
Large labelled resistor
Resistance result
100-ohm resistor color code
A four-band 100-ohm resistor is brown, black, brown, gold: 1, 0, ×10 and ±5%. A five-band 100-ohm resistor is brown, black, black, black followed by its tolerance band. The same colors apply to 1/4-watt, 1/2-watt, 1-watt and 2-watt versions because wattage is not encoded by the resistance bands.
How the bands create a value
Three- and four-band resistors use two significant digits. Five- and six-band resistors use three significant digits. The multiplier shifts the decimal position, the tolerance defines the allowed manufacturing range, and a sixth band can identify the temperature coefficient in parts per million per degree Celsius.
Decode from the tolerance end
The tolerance band is commonly spaced farther from the other bands. Hold that band on the right and read from left to right. When spacing is unclear, compare both orientations against a plausible preferred value and the component’s circuit role.
Preferred E-series comparison
E6, E12, E24, E48 and E96 preferred-number series divide each decade into progressively finer preferred values. The calculator reports the closest preferred value without silently changing the resistor you entered.
Resistor color code questions
What is the four-band code for 100 Ω?
Brown, black, brown, then the tolerance color—commonly gold for ±5%.
What is the five-band code for 100 Ω?
Brown, black, black, black, then the chosen tolerance color.
Does a 2-watt 100-ohm resistor use different colors?
No. The power rating usually changes the body size and construction, while the resistance bands remain based on 100 Ω and the selected tolerance.
Can a color-code calculation replace a meter reading?
No. Heat damage, fading, unusual standards and in-circuit parallel paths can make visual identification uncertain. Confirm critical components with appropriate test equipment.