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Resistors use colored bands instead of printed numbers to indicate their resistance value and tolerance.
This calculator decodes a 4-band or 5-band resistor's color sequence into its resistance in ohms, kilohms, or megohms, plus its tolerance percentage.
How it works
Choose 4-band or 5-band, then select the color of each band in order. The calculator converts the digit bands into a significant number, multiplies by the multiplier band's value, and reads the tolerance from the final band.
- Enter number of bands.
- Enter band 1 (1st digit).
- Enter band 2 (2nd digit).
- Enter band 3 (3rd digit — 5-band only).
- Enter multiplier band.
- Enter tolerance band.
- Click Calculate to see your results.
Examples
Brown-Black-Red-Gold
A 4-band resistor with brown, black, red, and gold bands reads 1,000 ohms (1 kΩ) with ±5% tolerance.
Who should use it
- Identifying an unmarked or unfamiliar resistor pulled from a parts bin.
- Checking your own manual color code reading for an electronics assignment.
Industry applications
- Electronics repair and prototyping
- Electrical engineering education
Advantages
- Supports both common 4-band and 5-band resistor formats.
- Automatically formats the result in Ω, kΩ, or MΩ as appropriate.
Limitations
- Doesn't support 6-band resistors (which add a temperature coefficient band).
Common mistakes to avoid
- Reading the bands in the wrong direction, which produces a completely different (and often nonsensical) value.
- Selecting 4-band mode while trying to enter a third digit band meant for a 5-band resistor.
Best practices
- If unsure of the reading direction, look for the tolerance band (commonly gold or silver) — it's always last.
Tips
- A quick way to remember the digit color order is the mnemonic "Black Brown Red Orange Yellow Green Blue Violet Gray White" (0 through 9).