Resistor Color Code Calculator

Decode resistor color bands to find resistance value, tolerance, and temperature coefficient. This tool processes all data locally in your browser. No information is ever sent to any server. Completely free, no registration required.

How to Use the Resistor Color Code Calculator

1. Enter your input values above
2. Results update automatically
3. Copy or download the output

What is a Resistor Color Code Calculator?

A Resistor Color Code Calculator decodes the colored bands on through-hole resistors into their resistance value and tolerance. The 4, 5, or 6 colored bands follow a standardized code — but memorizing it (Black=0, Brown=1, Red=2, Orange=3, Yellow=4, Green=5, Blue=6, Violet=7, Grey=8, White=9) is one of the most tedious parts of electronics. This calculator identifies resistor values from band colors and vice versa.

How Does It Work?

Select the number of bands (4, 5, or 6) and choose each band's color. The calculator decodes: significant digits, multiplier, tolerance (±%), and temperature coefficient (6-band only). Reverse mode: enter a resistance value and the calculator shows the corresponding color code. Results show the minimum and maximum resistance within tolerance.

Formula

4-band: [digit1][digit2] × 10^multiplier Ω ± tolerance%\n5-band: [digit1][digit2][digit3] × 10^multiplier Ω ± tolerance%\n6-band: same + temperature coefficient (ppm/°C)\n\nColor Code: 0=Black, 1=Brown, 2=Red, 3=Orange, 4=Yellow, 5=Green, 6=Blue, 7=Violet, 8=Grey, 9=White\nMultiplier: Gold=0.1, Silver=0.01\nTolerance: Brown=±1%, Red=±2%, Gold=±5%, Silver=±10%

Who Uses This Tool?

• Electronics hobbyists identifying mystery resistors in their parts bin
• PCB assemblers verifying component values before soldering
• Students learning electronics and the resistor color code
• Repair technicians identifying burnt or discolored resistors

Pro Tips

• Read the bands from the end closest to the first band. The tolerance band (gold/silver) is usually at the far end with a wider gap
• Measure with a multimeter for confirmation — color blindness, poor lighting, and discolored bands can cause 10× errors
• The mnemonic 'Better Be Right Or Your Great Big Venture Goes West' maps to 0-9. Add 'Gold Silver None' for multiplier/tolerance

Frequently Asked Questions about Resistor Color Code Calculator

Why do some resistors have 4 bands and others 5?

4-band = 2 significant digits (common for 5-10% tolerance). 5-band = 3 significant digits (for 1-2% precision resistors). 6-band adds temperature coefficient for precision applications.

How do I know which direction to read?

The tolerance band (gold ±5%, silver ±10%, brown ±1%) is almost always at the end. The gap between the tolerance band and the value bands is wider. When in doubt, measure.

Free online Resistor Color Code Calculator — no signup, 100% client-side processing. All data stays in your browser.