Resistor Color Code Calculator

Through-hole resistors use colored bands to encode their value. Once you learn the code, you can read any resistor at a glance. Until then — use this calculator.

How to Read a Resistor

Most resistors you’ll encounter are 4-band resistors. Precision resistors use 5 bands.

4-Band Resistors

Band	Meaning
Band 1	First significant digit
Band 2	Second significant digit
Band 3	Multiplier (×10ⁿ)
Band 4	Tolerance

Formula: Value = (Band1 × 10 + Band2) × Multiplier

Example: Yellow, Violet, Red, Gold = (4, 7) × 100 = 4700 Ω = 4.7 kΩ ±5%

5-Band Resistors

Band	Meaning
Band 1	First significant digit
Band 2	Second significant digit
Band 3	Third significant digit
Band 4	Multiplier
Band 5	Tolerance

Formula: Value = (Band1 × 100 + Band2 × 10 + Band3) × Multiplier

Identifying Band 1

The first band is closest to one end of the resistor. A few tips for orientation:

The tolerance band (Gold or Silver) is always last — start from the opposite end.
The first band is usually closer to a lead than the tolerance band.
If you see a wide gap before the last band, that’s the tolerance band — read left to right from the other side.

Common Resistor Values

Value	Color Code (4-band)	Common Use
10 Ω	Brown, Black, Black, Gold	Current limiting (high current)
100 Ω	Brown, Black, Brown, Gold	LED current limiting
330 Ω	Orange, Orange, Brown, Gold	LED with 3.3V supply
470 Ω	Yellow, Violet, Brown, Gold	General LED limiting
1 kΩ	Brown, Black, Red, Gold	Pull-up/pull-down
4.7 kΩ	Yellow, Violet, Red, Gold	I2C pull-up
10 kΩ	Brown, Black, Orange, Gold	GPIO pull-up/pull-down
100 kΩ	Brown, Black, Yellow, Gold	High-impedance pull-up

Tolerance Matters

The tolerance band tells you how close to the stated value the resistor actually is:

±1% (Brown) — Metal film, precision applications
±2% (Red) — Metal film
±5% (Gold) — Carbon film, most common
±10% (Silver) — Carbon composition, older stock

For most microcontroller applications (pull-ups, LED limiting, voltage dividers), ±5% is perfectly adequate.