To calculate a color code resistor, read the bands from left to right, keeping the metallic tolerance band (usually gold or silver) on the far right. For a standard 4-band resistor, the first two bands represent significant digits, the third is the decimal multiplier, and the fourth is the tolerance percentage. For example, a resistor with Brown (1), Black (0), Red (×100), and Gold (±5%) bands equals 1,000 ohms (1kΩ) with a 5% tolerance.
While the concept is simple, misreading a single band on a 1/4W carbon film component can lead to biasing a transistor incorrectly or setting the wrong cutoff frequency on an active filter. Below is the definitive reference guide to reading these components accurately on the bench.
The IEC 60062 Resistor Color Code Reference Table
The global standard for resistor color coding is IEC 60062. The table below maps every color to its corresponding digit, multiplier, tolerance, and temperature coefficient. Keep this chart at your workstation; it applies to 4-band, 5-band, and 6-band through-hole resistors.
| Color | Digit Value (Bands 1, 2, 3) | Multiplier (Band 3 or 4) | Tolerance (Band 4 or 5) | Temp Coeff (Band 6) |
|---|---|---|---|---|
| Black | 0 | ×1 (10⁰) | — | 250 ppm/°C |
| Brown | 1 | ×10 (10¹) | ±1% | 100 ppm/°C |
| Red | 2 | ×100 (10²) | ±2% | 50 ppm/°C |
| Orange | 3 | ×1,000 (10³) | ±0.05% | 15 ppm/°C |
| Yellow | 4 | ×10,000 (10⁴) | ±0.02% | 25 ppm/°C |
| Green | 5 | ×100,000 (10⁵) | ±0.5% | 20 ppm/°C |
| Blue | 6 | ×1,000,000 (10⁶) | ±0.25% | 10 ppm/°C |
| Violet | 7 | ×10,000,000 (10⁷) | ±0.1% | 5 ppm/°C |
| Grey | 8 | ×100,000,000 (10⁸) | ±0.01% | 1 ppm/°C |
| White | 9 | ×1,000,000,000 (10⁹) | — | — |
| Gold | — | ×0.1 (10⁻¹) | ±5% | — |
| Silver | — | ×0.01 (10⁻²) | ±10% | — |
How to read this table in practice: If you are reading a 5-band precision resistor (common in 1% metal film types), use the first three columns for digits, the fourth column for the multiplier, and the fifth column for tolerance. The sixth column (Temp Coeff) only applies to 6-band resistors, indicating how much the resistance drifts per degree Celsius of temperature change.
Rows and Bands People Get Wrong (Plus Faded Markings)
When you are sorting through a messy bin of salvaged components, certain bands and colors consistently cause calculation errors. Here are the specific edge cases to watch for:
The Multiplier Trap: Gold, Silver, and Black
Beginners often treat Gold and Silver as 'additions' rather than divisions. If your multiplier band is Gold, you are multiplying the significant digits by 0.1. For example, Brown (1), Black (0), Gold (×0.1) equals 1.0 ohm, not 10 ohms. Similarly, a Black multiplier means ×1 (10⁰). A resistor banded Red-Red-Black-Gold is 22 × 1 = 22 ohms, not 220 ohms.
Color Confusion: Red vs. Orange on Faded Resistors
Old carbon composition resistors and cheap carbon film types degrade under heat and UV exposure. Red bands frequently fade to a muddy pink or brown, while Orange bands fade to a pale yellow. If you calculate a value that doesn't exist in the standard E12 or E24 series (e.g., you read 32kΩ instead of the standard 33kΩ), your 'Red' band is likely an Orange band that has faded.
Standard Variants: IEC, MIL-SPEC, and Wire Color Confusion
A common point of confusion for DIYers crossing over from home wiring to electronics is mixing up component standards with mains wiring standards. It is critical to understand which standard applies to the physical object in your hand.
IEC 60062 vs. Wire Color Codes (NEC / IEC 60446)
The resistor color code is governed globally by IEC 60062. It has absolutely no relation to mains electrical wire colors. In US NEC wiring, a Black wire is 120VAC Hot, and White is Neutral. In IEC 60446 (UK/EU), Brown is Live and Blue is Neutral. Do not apply wire color logic to resistors. A black band on a resistor is always the digit zero; it does not mean 'hot' or 'ground'.
MIL-SPEC Reliability Bands
If you are working with surplus military equipment, you may encounter 5-band resistors that do not follow the standard IEC 60062 layout. Under older MIL-PRF-39008 specifications, the first four bands represent value and tolerance (like a standard 4-band resistor), but the fifth band indicates the component's reliability or failure rate per 1,000 hours (e.g., Brown = 1%, Red = 0.1%, Yellow = 0.001%). If a 5-band resistor's math doesn't make sense, check for a MIL-SPEC part number printed on the body.
Surface Mount (SMD) Variants
Through-hole color codes do not apply to SMD resistors. SMD components use a 3-digit or 4-digit numeric code (e.g., '103' = 10 × 10³ = 10kΩ) or the EIA-96 alphanumeric system for 1% precision parts. If you are transitioning from through-hole to SMD rework, you must switch to an EIA-96 lookup chart.
Frequently Asked Questions
How to calculate color code resistor for 5-band and 6-band types?
For a 5-band resistor, read the first three bands as significant digits, the fourth as the multiplier, and the fifth as tolerance. For example, Red (2), Violet (7), Black (0), Brown (×10), Brown (±1%) equals 2,700 ohms (2.7kΩ) at 1% tolerance. For a 6-band resistor, the calculation is identical to the 5-band, but the sixth band indicates the temperature coefficient (ppm/°C). A 6th band of Blue means the resistance will drift by 10 parts per million for every degree Celsius the temperature changes.
What if the resistor color code bands are unreadable or burnt?
If the bands are destroyed by heat, the internal carbon or metal film track has likely also degraded, meaning the resistor is out of spec even if you could read it. Safely remove the component from the circuit. Refer to the device's schematic or service manual for the original Bill of Materials (BOM) value. If no schematic is available, analyze the circuit topology (e.g., if it's a base-bias resistor for a 2N2222 transistor, it is likely in the 10kΩ to 47kΩ range) and replace it with a standard 1/4W metal film resistor of the suspected value to test.
Which way do I read the resistor bands if there is no spacing?
Manufacturers usually print the tolerance band (Gold or Silver) slightly separated from the value bands, or print the value bands closer to one lead. Always start reading from the end opposite the Gold/Silver band. If the resistor has no metallic tolerance band (e.g., a 5-band precision resistor where all bands are colors), use a DMM to measure the component. Compare your DMM reading to standard E-series values; if your meter reads 4.68kΩ, the resistor is almost certainly a standard 4.7kΩ (Yellow-Violet-Red) rather than a non-standard 4.6kΩ.
Does the body color of the resistor mean anything?
Yes, the body color often indicates the resistor's construction material and baseline tolerance. A beige or tan body typically indicates a carbon film resistor (usually 5% tolerance, 4-band). A blue body almost always indicates a metal film resistor (usually 1% or 2% tolerance, 5-band). A green body often denotes a high-precision or high-voltage metal film resistor, while a grey or dark green cylindrical body might indicate a wirewound power resistor. Always verify with the color bands, but body color is a great quick-sort method when organizing your component drawers.
