The exact color code for a 500Ω resistor is Green, Black, Brown (with a Gold tolerance band) for a standard 4-band resistor, or Green, Black, Black, Black (with a Brown tolerance band) for a 5-band precision resistor. However, before you dig through your component bins, you need to know that 500Ω is not a standard E-series value, meaning you are likely holding a 510Ω or 499Ω part.
The 500 Ohm Resistor Color Code Reference Table
Resistor color codes are read from left to right, starting with the band closest to the lead. The table below maps the exact band colors for a theoretical 500Ω resistor in both 4-band and 5-band formats, alongside the actual standard values (510Ω and 499Ω) you will find in commercial production.
| Band Position | 4-Band 500Ω (Custom) | 5-Band 500Ω (Custom) | 4-Band 510Ω (E24 Std) | 5-Band 499Ω (E96 Std) |
|---|---|---|---|---|
| Band 1 (1st Digit) | Green (5) | Green (5) | Green (5) | Green (5) |
| Band 2 (2nd Digit) | Black (0) | Black (0) | Brown (1) | Black (0) |
| Band 3 (3rd Digit / Mult) | Brown (×10) | Black (0) | Brown (×10) | White (9) |
| Band 4 (Mult / Tol) | Gold (±5%) | Black (×1) | Gold (±5%) | Black (×1) |
| Band 5 (Tolerance) | N/A | Brown (±1%) | N/A | Brown (±1%) |
In the 4-band system, the first two bands represent significant digits, the third is the multiplier, and the fourth is tolerance. In the 5-band system (used for 1% or tighter precision), the first three bands are significant digits, the fourth is the multiplier, and the fifth is tolerance. For a comprehensive breakdown of the underlying math, refer to the DigiKey Technical Article on Resistor Color Codes.
The "500 Ohm" Trap: Standard Values and Regional Codes
If you are designing a circuit or replacing a burnt component, requesting exactly "500 ohms" will usually result in a trip to a specialty supplier. The electronics industry relies on the E-series of preferred numbers (defined by IEC 60063) to standardize manufacturing.
- E12 / E24 Series (5% and 10% tolerance): The standard values in this decade are 470Ω and 510Ω. The number 500 is skipped entirely.
- E96 Series (1% tolerance): The standard values are 487Ω, 499Ω, and 511Ω. Again, exactly 500Ω is skipped.
If you have a resistor that looks like it reads 500Ω, you are almost certainly holding a 510Ω (Green-Brown-Brown) or a 499Ω (Green-Black-White-Black-Brown) part. Using a 510Ω instead of a theoretical 500Ω in a 5% tolerance circuit introduces only a 2% deviation, which is well within the Gold band's ±5% error margin.
- Misreading the 2nd band on 510Ω: Under warm LED bench lighting, the Brown (1) second band on a 510Ω resistor frequently looks Black (0). This leads hobbyists to misidentify a standard 510Ω part as a 500Ω part.
- Misreading the 3rd band on 499Ω: On a 5-band 499Ω resistor, the White (9) third band can look faded or silvery if the component has been subjected to heat. This causes readers to skip it or misread it as a multiplier.
- Multiplier confusion: A 4-band Green-Black-Orange reads as 50kΩ, not 500Ω. Ensure your multiplier band is Brown (×10), not Orange (×1,000).
Which Standard Applies to Your Region?
While electrical wiring color codes vary wildly by region—the US NEC uses Black/Red/Blue for 3-phase, the EU IEC 60446 uses Brown/Black/Grey, and the old UK standard used Red/Yellow/Blue—resistor color codes do not vary by region.
Resistor markings are universally governed by the IEC 60062 standard. A Green-Black-Brown resistor is 500Ω whether you are reading it in Texas, London, or Tokyo. There are no regional variants to memorize for through-hole axial resistors; the physics and the paint are globally standardized. For deeper reading on the international standard, consult the Electronics Tutorials IEC Color Code Guide.
Safe Interpretation: Faded Bands, Missing Markings, and Verification
Carbon film resistors subjected to prolonged over-current conditions will bake their paint. The epoxy body turns a crispy brown, and the color bands blister, fade, or carbonize. When visual interpretation of the IEC 60062 bands fails, you must rely on electrical measurement.
The "Lift One Leg" Rule for In-Circuit Measurement
The most common mistake when verifying a suspect resistor is measuring it while it is still fully soldered into the PCB. A multimeter sends a small test current through the probes to measure resistance. If the resistor is in-circuit, that test current will also flow through parallel traces, ICs, and capacitors, resulting in a "ghost reading" that is almost always lower than the resistor's actual value.
- De-energize the board: Remove all power sources and discharge large filter capacitors with a bleeder resistor.
- Isolate the component: Use a soldering iron to desolder and lift at least one leg of the resistor out of its PCB pad. This breaks the parallel circuit path.
- Measure: Place your multimeter probes directly on the exposed metal leads (not the painted body).
If you are troubleshooting a resistor in a mains-powered circuit (e.g., a snubber network across a TRIAC or a bleeder resistor on a tube amplifier power supply), never assume the circuit is dead just because it is unplugged. High-voltage capacitors can hold lethal charges for days. Always verify the circuit is dead with a known-good CAT III/IV meter, and use an insulated discharge tool before touching the resistor leads.
Precision Verification for 1% (E96) Resistors
If you are working with precision 1% resistors (like the 499Ω E96 standard) in a current-sense or transimpedance amplifier application, a standard 2-wire digital multimeter may not provide enough resolution. The resistance of your multimeter's test leads (typically 0.2Ω to 0.5Ω) will skew a 500Ω measurement by up to 0.1%.
For bench-level verification of precision resistors, use a 4-wire Kelvin measurement if your benchtop DMM supports it. This method forces current through one pair of leads and measures the voltage drop across a separate pair of sense leads, completely eliminating test-lead resistance from the equation. If your 5-band resistor measures between 494Ω and 504Ω on a 2-wire meter, it is well within the ±1% tolerance band, confirming it is a standard 499Ω part regardless of how faded the White third band might look under your magnifying lamp.
