FigureDesk

Resistor Color Code Calculator

Select the colors of each band on your resistor, in order from the end closest to a lead. FigureDesk reads them per the IEC 60062 standard color code and returns the resistance value and tolerance range.

Your numbers

Result

Resistance

1,000 Ω

Tolerance
± 5%
Range
950 – 1,050 Ω

Brown-Black, Red ×10^2, Gold ±5% → 10 × 100 = 1,000 Ω ±5%

How it works

Each color represents a digit, a power-of-ten multiplier, or a tolerance percentage, per the IEC 60062 standard. A 4-band resistor has two significant-digit bands, a multiplier band, and a tolerance band. A 5-band resistor adds a third digit band for an extra digit of precision, common on tighter-tolerance resistors.

value = (digit bands read as one number) × 10^multiplier
tolerance = ± tolerance band %

Worked example

A 4-band resistor with bands brown, black, red, gold:

  • Digits: brown = 1, black = 0 → 10
  • Multiplier: red = ×10² → 10 × 100 = 1000 Ω
  • Tolerance: gold = ± 5% → 950–1050 Ω

Important assumptions

  • Bands must be read in the correct order — starting from the end farthest from the tolerance band (usually gold or silver, set apart with a wider gap).
  • Supports the standard 4-band and 5-band color codes only — 6-band resistors (which add a temperature coefficient band) are not covered.
  • A resistor with no tolerance band at all is conventionally ±20%, which this calculator does not compute directly — select the closest documented tolerance band your resistor actually shows.

FAQ

Which end do I start reading from?

Start from the band closest to one end of the resistor body, away from the tolerance band. The tolerance band (commonly gold or silver) is usually spaced slightly farther from the others, which marks it as the last band, not the first.

What's the difference between 4-band and 5-band resistors?

A 4-band resistor encodes two significant digits, a multiplier, and a tolerance. A 5-band resistor encodes three significant digits before the multiplier and tolerance, giving one more digit of precision — common on resistors with tighter tolerances like ±1% or better.

Why can't gold or silver be a digit band?

Per IEC 60062, gold and silver are only ever used as multiplier bands (×0.1 and ×0.01) or tolerance bands (±5% and ±10%) — they have no assigned digit value, so they never appear in a digit-band position.

What if my resistor has no tolerance band?

A resistor with only 3 bands (no tolerance band at all) is conventionally rated ±20% tolerance by the standard — this calculator requires selecting a tolerance band explicitly rather than assuming that case for you.

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FigureDesk results are advisory and do not replace a licensed electrician, a qualified engineer, or the applicable local electrical code. Verify any electrical work against your local code and with a qualified professional before relying on it.