Calculators
Resistor Color Code Calculator
Decode 4-band and 5-band resistor color codes.
Decode standard 4-band or 5-band resistor markings. Every band is named in text, so the tool does not rely on color perception alone.
Resistance
1 kΩ ±5%
Tolerance range: 950 Ω to 1.05 kΩ
About This Tool
Resistor color bands encode significant digits, a multiplier, and tolerance without printing a long number on a small component. This calculator decodes standard 4-band and 5-band markings into resistance in ohms and shows the tolerance range. Each selection is written as a color name as well as represented by its band position, so the workflow does not depend on distinguishing colors visually.
How To Use It
- Choose 4-band or 5-band according to the resistor marking you are reading.
- Read from the end where the significant-digit bands begin; the tolerance band is commonly separated slightly from the others.
- Select each band by its written color name. Four-band codes use two significant digits; five-band codes use three.
- Read the resistance, tolerance percentage, and calculated minimum-to-maximum tolerance range.
Examples
Brown-black-red-gold
Brown (1), black (0), and red multiplier ×100 give 1,000 Ω or 1 kΩ. Gold means ±5%, giving a nominal range of 950 Ω to 1.05 kΩ.
Brown-black-black-red-brown
For a 5-band resistor, 1-0-0 with red ×100 gives 10,000 Ω or 10 kΩ. Brown tolerance means ±1%.
Red-red-gold-silver
Digits 2 and 2 with a gold ×0.1 multiplier give 2.2 Ω. Silver tolerance means ±10%.
Useful Notes
How 4-band codes work
The first two bands are significant digits. The third band is a power-of-ten multiplier and the fourth is tolerance. For example, brown-black-red is 10 × 100 = 1,000 Ω before tolerance is applied.
How 5-band codes work
Five-band codes use three significant digits followed by a multiplier and tolerance band. The extra digit supports finer nominal resistance values often seen on precision resistors.
Multiplier bands
Black through white represent multipliers from ×1 through ×1,000,000,000. Gold is ×0.1 and silver is ×0.01. Gold and silver are multipliers or tolerance colors, not significant-digit colors.
Tolerance range
Tolerance describes the permitted deviation from nominal resistance. The calculator reports nominal × (1 − tolerance/100) and nominal × (1 + tolerance/100). Actual resistance can also vary with temperature, aging, and operating conditions beyond this simple nominal-code interpretation.
Reading direction and limitations
Correct band order matters. The tolerance band is often spaced farther from the other bands, but physical markings vary. This tool decodes standard 4-band and 5-band value markings; it does not identify every specialized resistor marking, temperature coefficient band, SMD code, or manufacturer-specific scheme.
FAQ
What does a gold tolerance band mean?
Gold as the tolerance band means the nominal resistance tolerance is ±5%. Gold used in the multiplier position means ×0.1 instead.
What is the difference between 4-band and 5-band resistors?
A 4-band value uses two significant digits, while a 5-band value uses three. Both then use a multiplier and tolerance band.
How do I know which direction to read the bands?
The tolerance band is commonly separated from the digit and multiplier bands, so it is usually read last. If the physical marking is ambiguous, check the component documentation rather than guessing.
Does the calculator require me to distinguish colors visually?
No. Every selector and selected band is labelled with the color name in text, which also makes the interface more accessible when color perception is limited.
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