A 4-band resistor's value is calculated using a simple formula: (Band 1 × 10 + Band 2) × Multiplier (Band 3), with Band 4 indicating the manufacturing tolerance. The gold or silver tolerance band is always spaced slightly wider and placed on the far right. If you are holding a resistor with brown, black, red, and gold bands, the value is (1 × 10 + 0) × 100 = 1,000Ω (1kΩ) with a ±5% tolerance.
The Complete 4-Band Resistor Color Code Table
The following chart is based on the IEC 60062 international standard, which governs marking codes for resistors and capacitors globally. Read the bands from left to right, starting from the end closest to the lead.
| Color | Band 1 (1st Digit) | Band 2 (2nd Digit) | Band 3 (Multiplier) | Band 4 (Tolerance) |
|---|---|---|---|---|
| Black | 0 | 0 | 1Ω (×1) | — |
| Brown | 1 | 1 | 10Ω (×10) | ±1% |
| Red | 2 | 2 | 100Ω (×100) | ±2% |
| Orange | 3 | 3 | 1kΩ (×1,000) | — |
| Yellow | 4 | 4 | 10kΩ (×10,000) | — |
| Green | 5 | 5 | 100kΩ (×100,000) | ±0.5% |
| Blue | 6 | 6 | 1MΩ (×1,000,000) | ±0.25% |
| Violet | 7 | 7 | 10MΩ (×10,000,000) | ±0.1% |
| Gray | 8 | 8 | — | ±0.05% |
| White | 9 | 9 | — | — |
| Gold | — | — | 0.1Ω (×0.1) | ±5% |
| Silver | — | — | 0.01Ω (×0.01) | ±10% |
Rows People Get Wrong & Faded Band Recovery
Even experienced bench technicians misread bands under poor lighting or when dealing with sub-1-ohm current sense resistors. Here are the most common pitfalls and how to resolve them.
The Multiplier Trap: Gold and Silver
Most hobbyists memorize gold as ±5% tolerance. However, when gold or silver appears in the third position, it acts as a fractional multiplier for low-value current shunt resistors. A resistor banded Brown-Black-Gold-Gold is not 10Ω; it is 10 × 0.1 = 1Ω. Similarly, Green-Blue-Silver-Gold is 56 × 0.01 = 0.56Ω.
Lighting Distortion: Red vs. Orange
Under warm 3000K LED bench lighting, an orange band (3) is virtually indistinguishable from a red band (2). A 330Ω resistor (Orange-Orange-Brown) can easily be misread as 220Ω (Red-Red-Brown). Always verify critical bias resistors under 5000K daylight-balanced lighting or rely on your digital multimeter (DMM).
Safe Interpretation of Faded or Missing Markings
Carbon composition resistors from the 1970s and 1980s often suffer from heat-induced band fading. If the bands are illegible:
- Isolate the component: Never measure resistance in-circuit. Parallel paths through semiconductors and other resistors will yield falsely low readings.
- Use a high-precision DMM: A meter like the Fluke 87V or Brymen BM235 provides reliable readings down to 0.1Ω.
- Employ 4-wire Kelvin measurement: For resistors under 10Ω, standard DMM test leads introduce 0.2Ω to 0.5Ω of error. Use Kelvin clips to force current and sense voltage on separate paths, eliminating lead resistance entirely.
Global Standards: IEC 60062 vs Regional Wire Codes
A frequent point of confusion for beginners is assuming that electrical color codes change by region. It is critical to separate component marking codes from wire insulation codes.
Resistors are Universal
The resistance color code 4 band system is governed by IEC 60062. This standard is universal. A 4.7kΩ resistor (Yellow-Violet-Red-Gold) manufactured in Shenzhen, Munich, or Chicago will have the exact same color bands. There are no regional variants for resistor color codes.
Wire Codes are Highly Regional
Where regional standards clash is in mains wiring and DC harness insulation. Do not apply resistor color logic to house wiring or power supply cables:
- US/Canada (NEC Article 200/210): Uses Black, Red, and Blue for AC phases; White or Gray for neutral; Green/Bare for ground.
- EU/UK/AU (IEC 60446 / AS/NZS 3000): Uses Brown, Black, and Gray for AC phases; Blue for neutral; Green-Yellow stripe for earth.
- Old UK (Pre-2004): Used Red, Yellow, Blue for phases and Black for neutral. If you are troubleshooting legacy equipment, verify the manufacturing date to determine which wire code applies.
Frequently Asked Questions
How do I read a resistance color code 4 band if the tolerance band is missing?
If the fourth band is entirely missing or worn off, the resistor is likely an older carbon composition type with a default tolerance of ±20%. To determine orientation, look at the spacing: the first digit band is typically positioned closer to the lead wire than the multiplier band. If spacing is symmetrical, use your DMM to measure the value, then work backward to confirm which end is Band 1 based on standard E12/E24 series values.
What is the difference between a 4 band and 5 band resistor color code?
A 4-band code provides two significant digits (e.g., Brown-Black = 10), making it suitable for standard 5% or 10% tolerances. A 5-band code adds a third significant digit (e.g., Brown-Black-Black = 100) before the multiplier. You will almost exclusively see 5-band codes on 1% or 0.5% metal film resistors used in precision analog circuits, audio equipment, and measurement devices. If you see five bands, do not use the 4-band chart; the third band is a digit, not a multiplier.
Why does my resistance color code 4 band calculation not match my multimeter?
Discrepancies between the printed bands and your DMM reading usually stem from three causes:
- Tolerance drift: A 1,000Ω resistor with a ±5% gold band is legally allowed to measure anywhere between 950Ω and 1,050Ω straight from the factory.
- Temperature Coefficient (TempCo): Carbon film resistors have a high TempCo (often 500+ ppm/°C). If you are measuring a resistor that has been sitting in a cold garage (10°C) versus a warm bench (25°C), the value will shift.
- In-circuit measurement: If you are probing the resistor while it is still soldered to the PCB, the multimeter is measuring the equivalent resistance of the entire parallel network. Desolder at least one leg of the resistor to get an accurate, isolated reading.
