Decode a 4, 5 or 6-band resistor into its value — or go the other way and turn a resistance into colour bands. SMD codes, tolerance, value range and nearest standard value included.
Pick the band colours and this calculator reads off the resistance, tolerance and min/max range live; switch to value mode and it draws the bands for any resistance you type. It also decodes SMD chip codes and shows the nearest E-series part — free, private, and working entirely in your browser.
Works with 3-digit (103, 4R7, R47), 4-digit (4700, 0R50) and EIA-96 codes (01C, 68X).
Uses the standard IEC 60062 colour-code conventions and E-series preferred values. Printed bands can fade or be hard to tell apart — double-check critical values with a multimeter.
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Common resistor values
These are pre-decoded so you can grab the answer or share a direct link. Each opens this calculator with the bands already set.
Every colour carries up to three jobs: a digit, a multiplier (power of ten) and, for some colours, a tolerance or temperature coefficient. This is the full resistor colour-coding chart the calculator uses — the same table whether you spell it color or colour. The same colour coding — or color coding, in the American spelling — applies to a 4 band and a 5 band resistor alike; only the number of digit bands changes.
Resistor colour code chart: digit, multiplier, tolerance and temperature coefficient.
Colour
Digit
Multiplier
Tolerance
Temp. coeff (ppm/°C)
Black
0
×1
—
—
Brown
1
×10
±1%
100
Red
2
×100
±2%
50
Orange
3
×1k
—
15
Yellow
4
×10k
—
25
Green
5
×100k
±0.5%
—
Blue
6
×1M
±0.25%
10
Violet
7
×10M
±0.1%
5
Grey
8
×100M
±0.05%
—
White
9
×1G
—
—
Gold
—
×0.1
±5%
—
Silver
—
×0.01
±10%
—
How to read a resistor (4, 5 and 6 band)
Orient the resistor first: the tolerance band usually sits slightly apart from the rest, or gold/silver gives it away. Put that band on the right and read left to right.
4-band: digit, digit, multiplier, tolerance. Two significant figures — e.g. brown-black-red-gold = 10 × 100 = 1 kΩ ±5%.
5-band: digit, digit, digit, multiplier, tolerance. Three significant figures, so precise values like 4.7 kΩ read exactly — yellow-violet-black-brown-brown.
6-band: same as 5-band plus a sixth temperature-coefficient band (in ppm/°C) showing how much the value drifts with temperature.
A 3-band resistor is just a 4-band one with no tolerance band, which means ±20% by default.
SMD resistor code
Surface-mount resistors are too small for bands, so they carry a printed code instead. This calculator's SMD mode reads all the common formats:
3-digit: two significant digits then a power of ten — 103 = 10 × 10³ = 10 kΩ.
4-digit: three significant digits then a power of ten — 4700 = 470 × 10⁰ = 470 Ω.
R notation: the letter R is the decimal point — 4R7 = 4.7 Ω, R47 = 0.47 Ω.
EIA-96: a two-digit code (a lookup into the E96 series) plus a letter multiplier — 01C = 100 × 100 = 10 kΩ.
Resistor tolerance and value range
Tolerance is how far the real resistance may stray from the marked value. A 1 kΩ ±5% resistor is guaranteed only to land between 950 Ω and 1050 Ω. The calculator shows that min/max range for whatever you decode, which is exactly what matters when a resistor sets a current limit or a divider ratio. Resistors are made in preferred values (the E-series), so the tool also snaps any typed number to the nearest standard part you can actually buy.
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Frequently asked questions
What is the color code for a 1k ohm resistor?
A 1 kΩ (1000 Ω) resistor is brown, black, red on a 4-band part: brown = 1, black = 0, red = ×100, giving 10 × 100 = 1000 Ω. A gold 4th band means ±5%. As a 5-band part it reads brown, black, black, brown (100 × 10), with the tolerance band last.
What is the color code for a 10k ohm resistor?
A 10 kΩ (10,000 Ω) 4-band resistor is brown, black, orange: brown = 1, black = 0, orange = ×1000, so 10 × 1000 = 10,000 Ω. Add gold for ±5%. As a 5-band resistor it is brown, black, black, red — 100 × 100 — with the tolerance band on the end.
What is the color code for a 100 ohm resistor?
A 100 Ω 4-band resistor is brown, black, brown: brown = 1, black = 0, brown = ×10, giving 10 × 10 = 100 Ω, usually with a gold ±5% band. On a 5-band resistor it is brown, black, black, black (100 × 1) plus the tolerance band.
How do I read a 5-band resistor?
Hold it with the lone band or wider gap on the right. The first three bands are significant digits, the fourth is the multiplier, and the fifth is tolerance. So brown-black-black-brown-brown is 100 × 10 = 1000 Ω at ±1%. A 5-band part gives three digits instead of two, so it can show tighter values like 4.7 kΩ exactly.
How do I calculate a resistor's value from its colour bands?
Read the bands left to right with the tolerance band on the right, then calculate the value: turn the first bands into digits and multiply by ten to the power of the multiplier band. For brown-black-red that is 1, then 0, then ×100, so 10 × 100 = 1000 Ω. The calculator does this arithmetic for you and also works out the tolerance range — or type a value in and it calculates the bands instead.
How do I find the colour code of a resistance value?
Switch this tool to value-to-colour mode, type the resistance and pick a tolerance, and it draws the bands. By hand: write the value in significant figures (two for 4-band, three for 5/6-band), map each digit to its colour, then pick the multiplier band for the trailing zeros, and add a tolerance band.
What does an SMD resistor code like 103 or 4R7 mean?
On a 3-digit code the first two digits are significant and the third is the power of ten: 103 = 10 × 10³ = 10 kΩ. An R marks the decimal point, so 4R7 = 4.7 Ω. Four-digit codes use three significant figures (4700 = 470 Ω). EIA-96 codes are a two-digit lookup plus a letter multiplier, so 01C = 100 × 100 = 10 kΩ.
Which band is the tolerance band?
It is the last band and is usually set slightly apart from the others. Gold (±5%) and silver (±10%) only ever appear as tolerance (or multiplier) bands, so spotting one of those tells you which end you are reading from. If there is no tolerance band at all, the resistor is ±20%.