A standard 4-band resistor uses the first two bands for significant digits, the third for the multiplier, and the fourth for tolerance. A 5-band resistor adds a third significant digit for higher precision, and a 6-band adds a temperature coefficient. Use the master table below as your definitive reference for any resistor calculator color code lookup.
The Master Resistor Color Code Table
This table covers all standard through-hole axial resistors. Read the bands from left to right, keeping the tolerance band (usually Gold or Silver) on the far right.
| Color | Digit (1st, 2nd, 3rd Band) | Multiplier (10^x) | Tolerance | Temp Coeff (6th Band, ppm/°C) |
|---|---|---|---|---|
| Black | 0 | x1 (10^0) | - | 250 |
| Brown | 1 | x10 (10^1) | ±1% | 100 |
| Red | 2 | x100 (10^2) | ±2% | 50 |
| Orange | 3 | x1k (10^3) | - | 15 |
| Yellow | 4 | x10k (10^4) | - | 25 |
| Green | 5 | x100k (10^5) | ±0.5% | - |
| Blue | 6 | x1M (10^6) | ±0.25% | 10 |
| Violet | 7 | x10M (10^7) | ±0.1% | 5 |
| Gray | 8 | x100M (10^8) | ±0.05% | - |
| White | 9 | x1G (10^9) | - | - |
| Gold | - | x0.1 (10^-1) | ±5% | - |
| Silver | - | x0.01 (10^-2) | ±10% | - |
Standard Variants: EIA, IEC, and Legacy Codes
When searching for wiring, you will often see NEC vs IEC vs old UK color codes. For resistors, the regional and historical equivalents dictate how manufacturers print and space these bands:
- EIA RS-279 (US/Global Standard): This is the basis for 99% of online resistor calculator color code tools. It defines the standard 4, 5, and 6-band color mappings used by major manufacturers like Vishay and Yageo.
- IEC 60062 (International Standard): Technically identical to EIA in color values, but IEC strictly governs the physical spacing of the bands and the testing methodologies. If you are designing for global compliance, IEC 60062 is the governing document (All About Circuits).
- Old UK British Standard (BS 1852): Before color bands became universal, the UK and parts of Europe used alphanumeric coding to prevent fading. A 4.7kΩ resistor was printed as
4K7, and a 0.22Ω resistor asR22. The letter acts as the decimal point. You will still see this on older British equipment and some modern high-power cement resistors. - MIL-PRF-55342 (Military Spec): While modern military surface-mount resistors use 3-digit or 4-digit alphanumeric codes, older military through-hole resistors often used a 5-band system where the 5th band indicated reliability/failure rate (e.g., a Brown band for 1% failure rate per 1000 hours) rather than temperature coefficient.
Rows People Get Wrong (And How to Fix Them)
Even experienced engineers misread bands under poor bench lighting. Here are the most common errors when using a resistor calculator color code chart:
1. Gold and Silver as Multipliers
Most people memorize Gold as 5% tolerance and Silver as 10%. However, when they appear in the multiplier position (the third band on a 4-band resistor), they indicate fractional values. Gold is x0.1 and Silver is x0.01. A Brown-Black-Gold-Gold resistor is not 10 ohms; it is 1.0 ohm (10 x 0.1) with a 5% tolerance.
2. Black as a Multiplier
Because Black is '0' in the digit columns, beginners often multiply by zero when Black is the third band. Black as a multiplier means 10^0, which is x1. A Red-Red-Black-Gold resistor is 22 x 1 = 22 ohms, not 0 ohms.
3. Red vs. Orange on Faded Resistors
Under standard 4000K fluorescent or LED bench lights, red bands on older carbon film resistors (like the classic Vishay PR02 series) often fade to a pinkish-orange. If you are unsure, check the tolerance band. If the calculated value using 'Orange' (3) yields a non-standard E24 value (like 33kΩ instead of 30kΩ or 39kΩ), it is almost certainly a faded Red (2) yielding a standard 22kΩ.
4. Reading Direction
The tolerance band (Gold/Silver) is physically spaced slightly further from the other bands. Always orient the resistor so the grouped bands are on the left. If all bands are evenly spaced, look for a standard E-series value to determine the correct reading direction.
Faded or Missing Markings: Safe Interpretation
Carbon composition resistors from the 1970s and 80s are notorious for bands that rub off or fade to a uniform brown. Here is how to safely interpret them:
- Consult the Schematic/BOM: If you are repairing a commercial board, the Bill of Materials is your safest bet. Never guess on a safety-critical circuit (like a bleeder resistor in a power supply).
- Measure Out of Circuit: Desolder one leg and measure with a DMM. Ensure your fingers are not touching the metal probes or the resistor leads, as your body resistance (typically 50kΩ to 500kΩ) will skew readings on high-value resistors.
- Check for Physical Damage: If the resistor is blistered, cracked, or smells of burnt phenolic, its resistance has likely drifted permanently. A 100Ω carbon comp resistor that has overheated can easily drift to 150Ω or open entirely. Replace it with a modern metal film equivalent of the same wattage.
Resistor Calculator Color Code FAQ
How do I use a resistor calculator color code for a 5-band resistor?
A 5-band resistor simply adds a third significant digit for higher precision (typically 1% or 0.5% tolerance). The first three bands are your digits, the fourth is the multiplier, and the fifth is the tolerance. For example, Brown-Black-Black-Red-Brown translates to 1-0-0 (100) x 100 (Red) = 10,000 ohms (10kΩ) at ±1% tolerance. If your calculator only accepts 4 bands, use the first two digits, multiply, and verify that the result matches an E96 series value.
Why does my multimeter reading differ from the calculator's nominal value?
The calculator gives you the nominal value, but manufacturing tolerances allow for variance. A 10kΩ resistor with a Gold (±5%) tolerance band can legally measure anywhere between 9,500Ω and 10,500Ω and still be within spec. Additionally, cheap multimeters have an inherent accuracy specification (often ±0.5% + 2 digits). If your 10kΩ 1% resistor reads 9.98kΩ on your Fluke 117, both the resistor and the meter are functioning perfectly.
What does the 6th band (temperature coefficient) actually mean in practice?
The 6th band indicates how much the resistance changes with temperature, measured in parts per million per degree Celsius (ppm/°C). A Brown 6th band means 100 ppm/°C. In practice, if your 10kΩ resistor heats up by 10°C above room temperature, its value will shift by 100 x 10 = 1000 ppm, or 0.1%. For a 10kΩ resistor, that is a 10Ω shift. This is critical in precision analog circuits, audio crossovers, and sensor bridges, but entirely irrelevant for basic pull-up/pull-down or LED current-limiting applications.
