Resistor Color Code Calculator | 4/5/6-Band

How to Use the Calculator

1. Select the number of bands (4, 5, or 6).
2. Choose the color of each band using the dropdown.
3. The resistance value (Ω, kΩ, MΩ) and tolerance (±%) will be displayed automatically.
4. Color name labels are shown for accessibility, especially for users with color vision deficiency.

What is a resistor color code?

Resistors, essential components in electronic circuits, use color bands printed on their bodies to indicate resistance values (in ohms).

Why are colors used?

Since resistors are small and difficult to print numerical values on, color bands provide a highly visible way to convey information.

How the Calculation Works

Resistor color codes follow a simple rule. For a 4-band resistor, the first two bands represent digit values (e.g., Brown=1, Black=0 → 10), the third band is the multiplier (e.g., Red=×100), and the fourth is tolerance. So Brown-Black-Red-Gold means 10 × 100 = 1000Ω = 1kΩ (±5%). A 5-band resistor uses three digit bands, allowing more precise values such as 4.99kΩ. Once you learn the color-to-digit mapping, you can read most resistors at a glance without any tools.

How to Read Resistor Codes

For example, if the first three bands are brown, red, and red: Brown = 1, Red = 2, Red = ×100 → 1·2·×100 = 1200Ω = 1.2kΩ (± tolerance).

Common Use Cases

• Verifying parts during circuit design　When designing power supply or LED driver circuits, you can instantly verify the value of resistors on hand. This greatly speeds up the process of confirming that actual components match your schematic.
• Checking before soldering　Checking resistors with the tool just before soldering helps prevent wrong-value placement. Even when lighting conditions make colors hard to distinguish, the dropdown selection lets you confirm values confidently.
• Educational materials for classrooms　In electronics courses covering Ohm's Law, this tool makes a great hands-on exercise for reading color codes. Selecting bands and instantly seeing the result helps beginners build intuition quickly.
• Identifying second-hand or unmarked components　Resistors salvaged from scrap boards or unlabeled parts bags can be identified by their color code. Useful for organizing and reusing salvaged components.

Color Code Reference Table

Differences by Band Count

• 4-band: 2 digits + multiplier + tolerance (standard)
• 5-band: 3 digits + multiplier + tolerance (high precision)
• 6-band: 5-band + temperature coefficient (precision use)

About Temperature Coefficient (TCR)

The sixth band on a 6-band resistor indicates the Temperature Coefficient of Resistance (TCR), measured in ppm/°C. This tells you how much the resistance changes per million parts for each degree Celsius of temperature change. A resistor rated at 100 ppm/°C changes approximately 0.1% over a 10°C rise. Selecting low-TCR resistors is critical in precision measurement and temperature-compensated circuit designs.

Frequently Asked Questions (FAQ)

Q. Where do gold and silver bands appear?

Gold and silver appear in both the multiplier and tolerance positions. As a multiplier, gold means ×0.1 (10⁻¹) and silver means ×0.01 (10⁻²), used for sub-ohm values. As tolerance bands, gold indicates ±5% and silver ±10%.

Q. I can't tell which end to start reading from

The first band is generally closest to one end of the component. The tolerance band (gold, silver, etc.) is usually spaced slightly apart from the others — the end with more spacing is the tail. When unsure, calculate both directions and check which result falls on a standard E12 or E24 series value.

Q. When should I use 4-band vs. 5-band?

General-purpose resistors (±5%–±10% tolerance) are usually 4-band, while precision resistors (±1% or better) are typically 5-band. Six-band resistors are used for high-precision parts that specify a temperature coefficient. Check the part number or datasheet when in doubt.

Q. Can this tool do reverse lookup (resistance to color code)?

This tool supports color code → resistance value conversion. For the reverse direction — finding which color bands correspond to a given resistance — please visit the Resistor Color Code Reference page.