Resistor Color Code Calculator — Decode Any Resistor in Seconds
TL;DR
- Select each color band in the Resistor Color Code Calculator to get resistance, tolerance, and value range instantly
- Hold the resistor with the gold or silver tolerance band on the right, then read left to right
- 4-band resistors are most common; 5-band resistors add a third significant digit for higher precision
- Gold = plus or minus 5% tolerance; silver = plus or minus 10%; brown = plus or minus 1% for precision circuits
- Runs in your browser: no account required
The Resistor Color Code Calculator converts colored bands into a resistance value. Select the color of each band and the tool returns the resistance in ohms, kilohms, or megohms, the tolerance percentage, and the guaranteed minimum and maximum resistance within that tolerance.
How to Use the Resistor Color Code Calculator
Hold the resistor with the gold or silver band on the right. Read the remaining bands left to right. Select each band color from the dropdowns: most resistors have 4 bands, precision types have 5 or 6. For a 4-band resistor, the first two bands are significant digits, the third is a multiplier (power of 10), and the fourth is tolerance. The result shows the resistance value, tolerance, and the full value range.
When to Use This Calculator
Hobbyist projects: Confirm a resistor's value before soldering it in. Color bands are small and easy to misread under workshop lighting.
Student labs: Verify your color-band reading before using the value in an Ohm's law or voltage divider calculation.
Circuit debugging: When a circuit behaves unexpectedly, use the calculator to confirm every resistor matches the value the schematic calls for.
Parts ordering: Check the color code and resistance value before placing an order to avoid buying the wrong component.
Frequently Asked Questions
What do resistor color bands represent? Each color maps to a digit: Black=0, Brown=1, Red=2, Orange=3, Yellow=4, Green=5, Blue=6, Violet=7, Gray=8, White=9. A memory aid: "BB ROY of Great Britain Very Good Wife" covers the sequence in order. The second-to-last band is the multiplier and the final band is tolerance.
What is the difference between 4-band and 5-band resistors? A 4-band resistor has two significant digit bands, one multiplier, and one tolerance band, giving values like 10 kΩ ±5%. A 5-band resistor adds a third significant digit, giving values like 10.0 kΩ ±1%. Use 5-band resistors when a circuit needs tighter tolerances.
What does a gold or silver tolerance band mean? Gold means the actual resistance is within ±5% of the stated value. Silver means ±10%. A 100 Ω resistor with a gold band measures between 95 Ω and 105 Ω. Brown band resistors (±1%) are used when close tolerance matters.
The calculator is free and works on any device. No signup required.