How do I read a 4-band resistor?

The first two bands are significant digits, the third is the multiplier (a power of ten) and the fourth is the tolerance. For example brown-black-red-gold is 1, 0, times 100 = 1 kΩ at ±5%.

What is different about a 5-band resistor?

A 5-band resistor uses three significant-figure bands instead of two, then a multiplier and a tolerance band. The extra digit gives a more precise value, which is why precision (E96, 1% and tighter) parts use five bands.

What does the sixth band mean?

On a 6-band resistor the final band is the temperature coefficient (TCR) in ppm/°C — how much the resistance drifts per degree. Brown is 100 ppm/°C, red 50, and so on down to 1 ppm/°C for high-stability parts.

How are gold and silver bands handled?

As multipliers gold means ×0.1 and silver means ×0.01, which is how sub-10 Ω values are encoded. As tolerance bands gold means ±5% and silver means ±10%. The calculator applies whichever role the band is in.

Why does the value-to-colours mode say "nearest encodable value"?

Colour bands can only represent values rounded to 2 (4-band) or 3 (5/6-band) significant figures times a power of ten. If your input has more precision than that, the tool rounds to the closest band-representable value and tells you what it used.

Does this work for surface-mount (SMD) resistors?

No. SMD chip resistors are not colour-banded — they use printed numeric codes (such as the 3-digit, 4-digit or EIA-96 systems). This calculator covers axial through-hole resistors with painted colour bands.

Resistor Color Code Calculator

A resistor color code calculator that reads both directions: feed it the painted colour bands of a real resistor and it returns the resistance, tolerance and (on 6-band parts) the temperature coefficient — or type the resistance you want and it returns the exact band colours to look for. It supports 4, 5 and 6-band resistors and draws a live picture of the painted body so you can match it against the component in your hand.

How it works

Through-hole resistors encode their value with coloured stripes following the IEC 60062 standard. Each colour maps to a digit from 0 to 9 (black = 0, brown = 1, red = 2, up to white = 9). On a 4-band resistor the first two stripes are significant digits, the third is a multiplier (a power of ten — and gold/silver give the ×0.1 and ×0.01 needed for small values), and the fourth is the tolerance. A 5-band resistor adds a third digit band before the multiplier for one extra significant figure of precision, and a 6-band resistor adds a final temperature-coefficient stripe in ppm/°C.

The decode formula is simply:

R = (significant digits) × multiplier

with tolerance read straight off the tolerance band. For the reverse direction the tool normalises your target value to a significand and a power of ten, picks the matching digit and multiplier colours, and — because bands can only hold 2 or 3 significant figures — tells you the nearest encodable value when your input is more precise than the bands allow. Gold and silver are interpreted as multipliers or tolerances depending on which band slot they sit in.

Worked example

Take a 5-band resistor with stripes yellow-violet-black-brown-gold. The first three bands give the digits 4, 7, 0, so the significant figure is 470. Brown as a multiplier is ×10, so the resistance is 470 × 10 = 4,700 Ω = 4.7 kΩ. The gold band is ±5%, giving a tolerance window of 4,465 Ω to 4,935 Ω. Switch the tool to Resistance to colours, type 4.7 with the kΩ unit and ±5%, and it paints those same five stripes back for you.

Bands	Reading	Value	Tolerance
brown-black-red-gold	1 0 ×100	1 kΩ	±5%
yellow-violet-orange-gold	4 7 ×1k	47 kΩ	±5%
brown-black-black-brown-brown	1 0 0 ×10	1 kΩ	±1%
red-red-black-black-brown	2 2 0 ×1	220 Ω	±1%

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