How do I read the bands in the right order?

Hold the resistor so the tolerance band (usually gold or silver) is on the right. Read from the opposite end: the first two bands are digits, the third is the multiplier, and the rightmost is the tolerance.

What do gold and silver multiplier bands mean?

When gold or silver appears in the multiplier position it represents a fractional factor: gold multiplies by 0.1 and silver by 0.01. This lets the code express resistor values below 10 ohms.

What does the tolerance band tell me?

Tolerance is how far the real resistance may deviate from the nominal value. A ±5% gold band on a 1 kΩ resistor means the actual value lies between roughly 950 Ω and 1,050 Ω.

Does this calculator handle five- and six-band resistors?

This tool decodes the standard four-band code: two digit bands, one multiplier, and one tolerance band. Five- and six-band resistors add a third significant digit and a temperature-coefficient band that are not covered here.

Resistor Calculator

Band 1 (Digit)

Band 2 (Digit)

Band 3 (Multiplier)

Band 4 (Tolerance)

Resistance1.0 kΩ ±5%

Tolerance±5%

This resistor calculator decodes the four colored bands printed on a through-hole resistor into a resistance value and tolerance. The first two bands are significant digits, the third is a power-of-ten multiplier, and the fourth states the tolerance. Pick a color for each band and the tool returns the resistance, automatically formatted in ohms, kilohms, megohms, or gigohms.

Formula

R = (10 × d1 + d2) × multiplier

d1: First significant digit (Band 1 color, 0-9)
d2: Second significant digit (Band 2 color, 0-9)
multiplier: Power-of-ten factor from Band 3 color (×1 to ×10⁹, or ×0.1/×0.01)
R: Nominal resistance in ohms before applying tolerance

How it works

Choose the color of Band 1 and Band 2. Each maps to a digit from 0 (black) to 9 (white), and together they form the two significant figures.
Choose Band 3, the multiplier, which scales the two-digit number by a power of ten (brown ×10, red ×100, orange ×1,000, and so on, with gold ×0.1 and silver ×0.01).
Choose Band 4, the tolerance (for example gold ±5% or silver ±10%). The calculator multiplies the digits by the multiplier and displays the resistance with its tolerance band.

Worked examples

A resistor with bands brown, black, red, gold.

Brown = 1 and black = 0, so the two digits form 10.
Red multiplier = ×100, so R = 10 × 100 = 1,000 Ω.
Gold tolerance = ±5%.

1.0 kΩ ±5%.

A resistor with bands yellow, violet, orange, silver.

Yellow = 4 and violet = 7, so the two digits form 47.
Orange multiplier = ×1,000, so R = 47 × 1,000 = 47,000 Ω.
Silver tolerance = ±10%.

47.0 kΩ ±10%.

Frequently asked questions

How do I read the bands in the right order?: Hold the resistor so the tolerance band (usually gold or silver) is on the right. Read from the opposite end: the first two bands are digits, the third is the multiplier, and the rightmost is the tolerance.
What do gold and silver multiplier bands mean?: When gold or silver appears in the multiplier position it represents a fractional factor: gold multiplies by 0.1 and silver by 0.01. This lets the code express resistor values below 10 ohms.
What does the tolerance band tell me?: Tolerance is how far the real resistance may deviate from the nominal value. A ±5% gold band on a 1 kΩ resistor means the actual value lies between roughly 950 Ω and 1,050 Ω.
Does this calculator handle five- and six-band resistors?: This tool decodes the standard four-band code: two digit bands, one multiplier, and one tolerance band. Five- and six-band resistors add a third significant digit and a temperature-coefficient band that are not covered here.

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