Understanding Resistor Color Codes

Learn how to read resistor color codes for 4-band, 5-band, and 6-band resistors. Includes the color chart, tolerance bands, and tips for quick identification.

Why Resistors Use Color Codes

Through-hole resistors are too small to have their resistance value printed on them in readable text, so manufacturers use a system of colored bands painted around the body of the resistor. Each color represents a digit, a multiplier, or a tolerance value. This standardized system, established by the Electronic Industries Alliance (EIA), allows technicians and engineers worldwide to quickly identify a resistor's value without needing test equipment. While surface-mount resistors use a numerical code printed on their body, the color code system remains the standard for through-hole components used in prototyping, education, and many production circuits.

The Color-to-Number Mapping

Each color corresponds to a single digit from 0 through 9. Black is 0, Brown is 1, Red is 2, Orange is 3, Yellow is 4, Green is 5, Blue is 6, Violet is 7, Gray is 8, and White is 9. A common mnemonic to remember this sequence is "Better Be Right Or Your Great Big Venture Goes Wrong." The same colors are also used for the multiplier band, where the digit represents the power of ten by which the significant figures are multiplied. For example, Red as a multiplier means multiply by 10^2 (100), and Orange means multiply by 10^3 (1000). Gold and Silver are special multiplier colors representing 0.1 and 0.01 respectively.

Reading a 4-Band Resistor

A 4-band resistor has two significant digit bands, one multiplier band, and one tolerance band. The bands are read from left to right, starting from the end closest to a band (the tolerance band is usually spaced slightly apart or is Gold/Silver, which helps you orient the resistor correctly). For example, a resistor with bands Yellow-Violet-Red-Gold has significant digits 4 and 7 (giving 47), a multiplier of Red (10^2 = 100), and a tolerance of Gold (plus or minus 5%). The resistance value is 47 * 100 = 4700 ohms, or 4.7 kilohms, with a tolerance of plus or minus 5%.

Reading a 5-Band Resistor

Precision resistors often use five bands: three significant digit bands, one multiplier band, and one tolerance band. The extra digit band provides greater precision. For example, bands of Brown-Black-Black-Brown-Brown give significant digits 1, 0, 0 (forming 100), a multiplier of Brown (10^1 = 10), and a tolerance of Brown (plus or minus 1%). The resistance is 100 * 10 = 1000 ohms, or 1 kilohm, with 1% tolerance. Five-band resistors are standard in applications that require tighter resistance values, such as precision measurement circuits, reference voltage dividers, and instrumentation.

The Tolerance Band

The tolerance band indicates how much the actual resistance can deviate from the stated value. Brown indicates plus or minus 1%, Red indicates 2%, Gold indicates 5%, and Silver indicates 10%. If there is no tolerance band, the tolerance is assumed to be 20%. For a 1000-ohm resistor with Gold tolerance (5%), the actual value can range from 950 to 1050 ohms. Tolerance matters significantly in sensitive circuits like voltage dividers, filter networks, and bridge circuits, where small resistance deviations can cause noticeable performance changes. For general-purpose applications like LED current limiting, 5% or even 10% tolerance is usually adequate.

6-Band Resistors and Temperature Coefficient

A 6-band resistor includes all five bands of a 5-band resistor plus an additional sixth band for the temperature coefficient of resistance (TCR). The TCR indicates how much the resistance changes per degree Celsius of temperature change, measured in parts per million per degree Celsius (ppm/C). Brown indicates 100 ppm/C, Red indicates 50 ppm/C, Orange indicates 15 ppm/C, Yellow indicates 25 ppm/C, and Blue indicates 10 ppm/C. Lower TCR values mean the resistor is more stable over temperature variations. Six-band resistors are used in high-precision and high-reliability circuits, such as medical devices, aerospace electronics, and calibration equipment.

Common Pitfalls When Reading Color Codes

Several issues can make reading resistor color codes tricky. Orienting the resistor correctly is the most common challenge: always start reading from the end nearest to a band, and remember that the tolerance band (Gold, Silver, or a wider gap) is always on the right. Distinguishing similar colors under poor lighting can be difficult, particularly Red versus Orange, or Brown versus Violet on older or dirty resistors. When in doubt, always verify with a multimeter. Another common mistake is confusing 4-band and 5-band resistors; check whether the resistor has two or three significant digit bands before reading. Some manufacturers use body color as an additional identifier, which can add to the confusion.

Quick Reference and Practical Tips

Keep a resistor color code chart at your workstation for fast reference until you have the colors memorized. Use a digital multimeter to verify your reading, especially for resistors from salvaged boards where band colors may have faded. Organize your resistor collection in labeled compartments or on labeled strips of tape to avoid needing to decode colors repeatedly. When ordering resistors, note that the E-series standard (E12, E24, E96) defines preferred values. For example, the E12 series includes 12 values per decade: 10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, and 82. Knowing these preferred values helps you quickly estimate a resistor value even if you are unsure about one color band.

Try These Calculators

Put what you learned into practice with these free calculators.

Resistor Color Code Calculator Resistor Tolerance Calculator SMD Resistor Code Calculator