Resistor Color Code Calculator
Decode 4-band and 5-band resistor color codes to find resistance value and tolerance.
Resistor Color Code Chart
Black=0, Brown=1, Red=2, Orange=3, Yellow=4, Green=5, Blue=6, Violet=7, Gray=8, White=9. For 4-band resistors: Band 1 and 2 are digits, Band 3 is the multiplier, Band 4 is tolerance. For 5-band: Bands 1–3 are digits, Band 4 is multiplier, Band 5 is tolerance.
Tolerance Colors
Gold=±5%, Silver=±10%, Brown=±1%, Red=±2%, Green=±0.5%, Blue=±0.25%.
Frequently Asked Questions
How do I read a 4-band resistor?
Hold the resistor with the tolerance band (gold, silver, or no band) on the right. Read left to right: first color is first digit, second color is second digit, third color is the multiplier (the power of 10 to multiply by), fourth color is tolerance. Red-Violet-Brown-Gold: 2, 7, ×10¹, ±5% = 270 ohms ±5%. If you can't tell which end to start from, try both orientations and see which gives a standard resistor value.
Why do resistors use color codes?
Resistors are physically tiny components with cylindrical bodies — there is no flat surface large enough to print readable numbers reliably. Color bands can be applied uniformly, read from any angle, and remain readable even when a component is soldered into a circuit board. The color code system was standardized in the 1920s and remains universally used in electronic components today.
What are common resistor values?
Resistors come in standard value series (E12, E24, E48, E96) rather than arbitrary values, to minimize the number of different values manufacturers need to produce. Common values you will encounter frequently: 100Ω, 220Ω, 330Ω, 470Ω, 1kΩ, 2.2kΩ, 4.7kΩ, 10kΩ, 47kΩ, 100kΩ, 1MΩ. LED current-limiting resistors are often 220Ω–470Ω. Pull-up/pull-down resistors in digital circuits are typically 10kΩ.
What does the tolerance band mean?
Tolerance tells you how much the actual resistance value may vary from the marked value. A 10kΩ resistor with ±5% tolerance (gold band) can actually be anywhere from 9,500Ω to 10,500Ω. For most general electronics this is fine. Precision circuits may require ±1% (brown band) or tighter. Always check if your application needs tight tolerance before assuming the cheapest resistor will work.
How do I identify the tolerance band?
The tolerance band is usually gold or silver (the most common colors), and it is typically spaced slightly further from the other bands to indicate it is read last. If the bands appear evenly spaced and ambiguous, look up the value in both orientations — only one will give a standard resistor value. Some modern resistors use a band at one end that is noticeably wider than the others to indicate the starting end.