A standard resistor 4 band colour code uses the first two bands for significant digits, the third band for the decimal multiplier, and the fourth band for the manufacturing tolerance. Always orient the component so the tolerance band (typically gold or silver) is on the far right, then read left-to-right to calculate the exact ohmic value.
The Complete Resistor 4 Band Colour Code Reference Table
Keep this chart at your bench. The international standard governing these markings is IEC 60062, which harmonized the older US-based EIA RS-279 standard. While 5-band and 6-band resistors exist for 1% precision metal film parts, the 4-band system remains the universal standard for general-purpose 5% and 10% carbon and thick-film resistors.
| Colour | Band 1 & 2 (Digit) | Band 3 (Multiplier) | Band 4 (Tolerance) |
|---|---|---|---|
| Black | 0 | ×1 Ω | — |
| Brown | 1 | ×10 Ω | ±1% (Rare on 4-band) |
| Red | 2 | ×100 Ω | ±2% (Rare on 4-band) |
| Orange | 3 | ×1 kΩ | — |
| Yellow | 4 | ×10 kΩ | — |
| Green | 5 | ×100 kΩ | ±0.5% (Rare on 4-band) |
| Blue | 6 | ×1 MΩ | ±0.25% (Rare on 4-band) |
| Violet | 7 | ×10 MΩ | ±0.1% (Rare on 4-band) |
| Gray | 8 | ×100 MΩ | ±0.05% (Rare on 4-band) |
| White | 9 | ×1 GΩ | — |
| Gold | — | ×0.1 Ω | ±5% |
| Silver | — | ×0.01 Ω | ±10% |
| None | — | — | ±20% |
What Each Band Means in Practice (IEC 60062 vs. EIA)
Understanding the physical manufacturing context prevents reading errors. Under the IEC 60062 standard, the body of the resistor is typically painted a neutral tan, blue, or gray. The coloured bands are silk-screened or painted on.
- Bands 1 & 2 (Significant Digits): These establish the base number. A 4-band system only supports two significant digits, meaning the base number will always be between 10 and 99 (or 01 to 09 for sub-ohm values).
- Band 3 (Multiplier): This is not a digit to append; it is a power of ten. An orange band means "add three zeros" (×1,000). A gold band in the third position is a fractional multiplier (×0.1), used for values like 4.7 Ω (Yellow-Violet-Gold-Gold).
- Band 4 (Tolerance): This dictates the acceptable deviation from the nominal value. A 1 kΩ resistor with a ±5% gold band will measure anywhere between 950 Ω and 1,050 Ω on your multimeter and still be considered in-spec by the manufacturer.
While the older US EIA RS-279 standard used identical colours, modern global supply chains strictly adhere to IEC 60062. You will not encounter regional colour variations for standard through-hole resistors, though surface mount (SMD) resistors use an entirely different alphanumeric printing system (like the EIA-96 code).
Rows People Get Wrong: Common Misreads and Faded Band Fixes
Bench experience reveals that visual inspection fails under specific conditions. Here are the most common traps and how to bypass them.
The Red vs. Orange Fade
On older carbon composition resistors, or cheaply manufactured carbon film parts exposed to high ambient heat, red bands frequently oxidize and fade to a muddy orange. If you read a faded band as orange (3) instead of red (2), a 2.2 kΩ resistor gets misidentified as 3.3 kΩ—a 50% error that will completely alter the biasing of a transistor circuit.
Gold as a Multiplier vs. Tolerance
Beginners often assume gold always means 5% tolerance. If a resistor is marked Green-Blue-Gold-Gold, the first gold band is the multiplier (×0.1), making the value 5.6 Ω, not 56 Ω. The position dictates the function: Band 3 is always the multiplier, Band 4 is always the tolerance.
Decision Path: Verify and Pick the Exact Replacement
When replacing a damaged resistor or designing a new board, you cannot simply order the exact calculated mathematical value. Resistors are manufactured in standardized "E-series" values. Use this decision tree to terminate your selection process with a concrete, purchasable part number.
| Condition / Step | Action to Take | Concrete Outcome |
|---|---|---|
| Step 1: Calculate required theoretical resistance (e.g., using Ohm's Law for an LED current limiter: 5V source, 2V LED drop, 20mA target = 150 Ω). | Identify the nearest standard E-series value. 5% resistors use the E24 series; 1% use E96. | Target value identified: 150 Ω. |
| Step 2: Check if the calculated value exists in the E24 series (10, 11, 12, 13, 15, 16, 18, 20, 22, 24, 27, 30, 33, 36, 39, 43, 47, 51, 56, 62, 68, 75, 82, 91). | If yes, select that exact multiplier decade. If no, round to the nearest available E24 value. | 15 is in the E24 series. Multiplier is ×10. Final value: 150 Ω. |
| Step 3: Calculate power dissipation (P = I²R). For 20mA through 150 Ω, P = 0.06W. | Select a physical package with a power rating at least 2x the calculated dissipation for thermal reliability. | 0.06W × 2 = 0.12W. A standard 1/4W (0.25W) axial resistor is safe. |
| Step 4: Translate to 4-band colour code for bench verification. | Map digits and multiplier: 1 (Brown), 5 (Green), ×10 (Brown), 5% (Gold). | Final Pick: Brown-Green-Brown-Gold 1/4W 5% Carbon/Metal Film Resistor. |
If your theoretical calculation lands on a non-standard number—for example, 165 Ω—you do not custom-order a 165 Ω resistor. You look at the E24 series, see that 16 and 18 are the bounding values, and pick the closest one (160 Ω or 180 Ω) based on whether your circuit needs to bias slightly higher or lower in current. For general hobbyist and repair work, stocking a standard E12 or E24 assortment kit (typically costing $10–$15 for 600+ pieces) covers 99% of all 4-band replacement scenarios you will encounter on the bench.
