Resistor Color Code Calculator
Decode any resistor's color code to find its resistance value and tolerance.
📖 What is a Resistor Color Code?
Resistors - the tiny components that limit current flow in electronic circuits - are usually too small to have their value printed in numbers. Instead, they use a standardised system of colour bands that encode the resistance value and tolerance. The resistor colour code was standardised by the Electronic Industries Alliance (EIA) and is used worldwide.
A 4-band resistor has two significant figure bands, one multiplier band, and one tolerance band. This encodes values to two significant figures, suitable for general-purpose resistors with ±5% or ±10% tolerance.
A 5-band resistor adds an extra significant figure, encoding the value to three significant figures. These are used for precision resistors with ±1% or better tolerance, where the extra digit provides more accurate specification.
Reading the code is simple once you know the colour-to-number mapping: Black=0, Brown=1, Red=2, Orange=3, Yellow=4, Green=5, Blue=6, Violet=7, Grey=8, White=9. The multiplier band uses these plus gold (×0.1) and silver (×0.01). The tolerance band uses gold (±5%), silver (±10%), and colours for precision values.
📐 Formula
📖 How to Use This Calculator
💡 Example Calculations
Example 1 - 4-band: Brown-Black-Red-Gold
Example 2 - 5-band: Red-Yellow-Orange-Red-Brown
Frequently Asked Questions
🔗 Related Calculators
How do I read a resistor color code?
For a 4-band resistor: Band 1 = first digit, Band 2 = second digit, Band 3 = multiplier (power of 10), Band 4 = tolerance. Read them in order from the band closest to the end of the resistor. Example: Brown-Black-Red-Gold = 1, 0, ×100, ±5% = 1000Ω ±5% = 1kΩ.
What is the difference between 4-band and 5-band resistors?
4-band resistors have 2 significant figure bands + 1 multiplier + 1 tolerance. 5-band resistors have 3 significant figure bands + 1 multiplier + 1 tolerance, allowing more precise values. Precision resistors (1% or better) are usually 5-band.
What do the tolerance colors mean?
Brown = ±1%, Red = ±2%, Green = ±0.5%, Blue = ±0.25%, Violet = ±0.1%, Gold = ±5%, Silver = ±10%, None = ±20%.
What is E24 series?
Resistors come in standard values based on the E-series. E24 (24 values per decade) is common for ±5% tolerance resistors. Common values include: 10, 11, 12, 13, 15, 16, 18, 20, 22, 24, 27, 30, 33, 36, 39, 43, 47, 51, 56, 62, 68, 75, 82, 91 - and their multiples.
What if a resistor has no color bands at all?
Plain resistors without color bands are typically fusible resistors or power resistors where the value is printed directly on the body. Some surface mount resistors (SMD) use a 3- or 4-digit numerical code instead of color bands.
How do you read a 4-band resistor color code?
For a 4-band resistor: Band 1 = first significant digit. Band 2 = second significant digit. Band 3 = multiplier (number of zeros). Band 4 = tolerance. Color values: Black=0, Brown=1, Red=2, Orange=3, Yellow=4, Green=5, Blue=6, Violet=7, Grey=8, White=9. Multipliers: Black=x1, Brown=x10, Red=x100, Orange=x1000, Yellow=x10000. Tolerances: Gold=5%, Silver=10%. Example: Red-Red-Brown-Gold = 2-2-x10-5% = 220 ohms 5%.
What are the standard resistor values (E-series)?
Resistors are manufactured in standard E-series values rather than every possible number. E12 (12 values per decade, 10% tolerance): 10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82 and their multiples. E24 (24 values, 5% tolerance) fills in between. E96 (96 values, 1% tolerance) provides finer increments. If you calculate a needed resistance of 427 ohms, the nearest E24 value is 430 ohms. This is why circuit design often requires standard values rather than exact calculated values.
How do I read a 6-band resistor color code?
6-band resistors add a temperature coefficient band after the tolerance band. Bands 1-3 are the three significant digits, band 4 is the multiplier, band 5 is tolerance, and band 6 is temperature coefficient (ppm per degree C). Brown = 100 ppm, Red = 50 ppm. Standard 4 and 5-band resistors are far more common; 6-band are used in precision applications.