To calculate the resistor color code, read the bands from left to right: the first two or three bands represent significant digits, the next is the multiplier, and the final band is the tolerance. Below is the master reference chart based on the global IEC 60062 standard.
The Complete Resistor Color Code Reference Table
This table covers all standard through-hole axial resistor bands. Read the digit columns for the first 2 or 3 bands, apply the multiplier, and check the final band for tolerance.
| Color | Digit (1st/2nd/3rd Band) | Multiplier (4th/3rd Band) | Tolerance (Final Band) | Temp Coeff (6th Band ppm/°C) |
|---|---|---|---|---|
| Black | 0 | ×1 (10⁰) | — | 250 |
| Brown | 1 | ×10 (10¹) | ±1% (F) | 100 |
| Red | 2 | ×100 (10²) | ±2% (G) | 50 |
| Orange | 3 | ×1k (10³) | — | 15 |
| Yellow | 4 | ×10k (10⁴) | — | 25 |
| Green | 5 | ×100k (10⁵) | ±0.5% (D) | — |
| Blue | 6 | ×1M (10⁶) | ±0.25% (C) | 10 |
| Violet | 7 | ×10M (10⁷) | ±0.1% (B) | 5 |
| Gray | 8 | — | ±0.05% (A) | — |
| White | 9 | — | — | — |
| Gold | — | ×0.1 (10⁻¹) | ±5% (J) | — |
| Silver | — | ×0.01 (10⁻²) | ±10% (K) | — |
Decoding the Bands and Avoiding Common Mistakes
Resistor band configurations depend on the component's tolerance and the E-series standard it belongs to. A standard 5% carbon film resistor uses the E24 series and requires only 4 bands (two significant digits, one multiplier, one tolerance). A 1% metal film resistor uses the E96 series, requiring 5 bands (three significant digits, one multiplier, one tolerance) to capture values like 4.7kΩ or 2.21kΩ. 6-band resistors add a temperature coefficient (tempco) band, critical for precision analog circuits where ambient heat shifts resistance.
Worked Example: 5-Band Calculation
Consider a 5-band resistor with Brown - Black - Black - Red - Gold bands:
- Brown (1st): Digit 1
- Black (2nd): Digit 0
- Black (3rd): Digit 0
- Red (Multiplier): ×100
- Gold (Tolerance): ±5%
Calculation: 100 × 100 = 10,000 ohms, or 10kΩ ±5%.
Rows and Scenarios People Get Wrong
Even experienced technicians misread resistors under poor bench lighting. Watch for these specific traps:
- Gold/Silver as Multipliers vs. Tolerance: Gold and silver can appear as the multiplier band (yielding values under 10 ohms, like a 4.7Ω current sense resistor) or as the tolerance band. If gold is the second to last band on a 4-band resistor, it's a multiplier. If it's the very last band, it's a 5% tolerance.
- Red vs. Brown in Faded Lighting: A red band (digit 2) and a brown band (digit 1) look nearly identical under warm LED bench lights. Misreading a 220Ω current-limiting resistor as 120Ω will overdrive your LEDs. Always verify with a multimeter if the hue looks muddy.
- Reading Direction: The tolerance band (usually gold, silver, or brown) is often spaced slightly further away from the other bands. If the spacing is symmetrical, start reading from the end that does not begin with a gold or silver band, as those colors are never used as the first significant digit.
Regional and Historical Standard Variants
While the IEC 60062 standard is the universal baseline today, you may encounter legacy variants in older equipment:
- Old British BS1852 / Body-Tip-Dot System: Before color bands wrapped entirely around the cylinder, resistors used a painted body color, a painted tip color, and a dot. The body was the first digit, the tip was the second, and the dot was the multiplier. A brown body, black tip, and red dot equals 10 × 100 = 1kΩ.
- US MIL-R-55342 / MIL-Spec 5th Band: In older military avionics and telecom gear, a standard 4-band resistor might feature a 5th band indicating failure rate rather than a 3rd significant digit. A brown 5th band on a military spec resistor meant a 1% failure rate per 1,000 hours, not a digit '1'.
Safe Interpretation When Markings are Faded or Burnt
When a resistor overheats, the epoxy coating scorches, and the color bands blister or turn uniformly black. Never trust the color code of a burnt resistor. The thermal stress permanently alters the crystalline structure of the metal film or carbon track, meaning the physical resistance has drifted far outside its tolerance, even if the bands are still legible.
If you measure a suspected 10kΩ pull-up resistor with a multimeter while it is still soldered to the PCB, you might read 4.2kΩ and assume the resistor is damaged. In reality, you are measuring the parallel resistance of the microcontroller's internal protection diodes and the load. Always desolder at least one leg of the resistor from the board to isolate it before taking a definitive resistance reading.
If the markings are entirely gone and the component is physically intact, follow this diagnostic sequence:
- Isolate and Measure: Desolder one leg and measure with a calibrated digital multimeter. If it reads open (OL), the internal trace has fractured and the part is dead.
- Deduce from Circuit Topology: If the resistor is completely destroyed and unreadable, look at its function. Resistors tied from a microcontroller GPIO to VCC are almost always 10kΩ pull-ups. Resistors in series with a standard 5mm LED from a 5V rail are typically 220Ω or 330Ω. Base resistors for small-signal transistors (like a 2N2222) usually fall between 1kΩ and 4.7kΩ.
- Check the Schematic or Service Manual: For commercial PCBs, locate the component designator (e.g., R42) on the silkscreen and cross-reference the board's schematic. Never blindly replace a burnt resistor without identifying why it burnt; a failed shorted semiconductor downstream is usually the root cause.
For verified, safe testing procedures on isolated components, refer to standard multimeter resistance measurement guidelines to ensure your test leads and probes aren't introducing parasitic resistance into your low-ohm readings.
