How do I read the color bands on a resistor?

Hold the resistor with the tolerance band, often gold or silver, on the right and read left to right. Pick 4, 5 or 6 bands and set each color. Digits, multiplier and tolerance combine into the value.

What is the difference between 4-band, 5-band and 6-band resistors?

A 4-band resistor has two digit bands, a multiplier and a tolerance. A 5-band adds a third digit for precision. A 6-band adds a temperature coefficient in ppm/K as the final band.

How do I find the color bands for a resistance value I need?

Type a value such as 4.7k, 4k7, 2M2 or 220 in the resistance field. The tool shows the band colors. Values must be between 0.01 ohm and 99 gigaohms, and within the range for the chosen band count.

How do I read the code printed on a surface-mount resistor?

Use the SMD marking field. It accepts 3 or 4 digit codes like 103 or 2201, R or k notation like 4R7 and 4k7, and EIA-96 codes like 01C. It then shows the value and a typical tolerance.

Can it calculate resistors for an LED or a voltage divider?

Yes. It has an LED series resistor calculator giving exact, nearest E12 and E24 values plus power, a voltage divider that picks E24 resistors, and series and parallel totals for a list of values.

Yes. Every tool is free to use, with no account and no credit card. The work runs on your device rather than on our servers, which is what keeps it free to run.

Does it work on mobile?

Yes. It runs in current mobile browsers on iOS and Android, with nothing to install.

🎛️

Free Resistor Color Code Calculator

Decode 4, 5, and 6-band resistors into resistance, tolerance, and temperature coefficient. Pick band colors and read the value instantly with a visual resistor.

Runs in your browserNo sign-up, no pop-upsNo login requiredFree forever

Works offline once loaded

Read from this end

1 kΩ ±5%

±5% tolerance

Range: 950 Ω – 1.05 kΩ

Standard E24 value

Digit 1

Digit 2

Multiplier

Tolerance

Wrong way round?

💡 Read bands from the end with the tolerance band (often gold or silver) on the right. 4-band resistors use two significant digits; 5- and 6-band use three for tighter precision.

Common uses

Read 4-Band Resistor ColorsDecode the most common resistor type: two digits, a multiplier, and a tolerance band.
Decode 5-Band Precision ResistorsRead three-significant-digit resistors used in precision circuits.
Decode 6-Band ResistorsRead precision resistors that also specify a temperature coefficient.
Learn the Resistor Color CodePractice reading bands and check your answers while learning electronics.
Pick Resistors for Arduino & LEDsIdentify the resistor you need for LED current limiting and pull-ups.

How It Works

This tool works entirely in your browser using a hand-written lookup table that encodes the IEC 60063 resistor color code standard — no library, no server. It works in both directions: pick band colors to decode a resistance value, or type a resistance to find the corresponding band colors.

1
Color-to-value lookup
Each color maps to a fixed digit (0–9), multiplier (0.01 Ω to 1 GΩ), tolerance (±0.05 % to ±10 %), and temperature coefficient (1–250 ppm/K). These are stored in a single COLORS table compiled directly from the IEC 60063 standard — no network fetch, no parsing at runtime.
2
Resistance arithmetic
In Decode mode the tool reads each selected band's role (digit, multiplier, tolerance, optionally tempco), concatenates the digit values into a number, then multiplies by the multiplier band's factor. In Find mode it runs the reverse: it factors the entered ohm value into significant digits and a power-of-ten exponent, then looks up the matching bands.
3
E-series nearest-value check
After decoding or encoding, the tool checks whether the result lands on a purchasable standard value using the appropriate E-series table (E12 for ±10 %, E24 for ±5 %, E48 for ±2 %, E96 for tighter tolerances). If the value is non-standard, it surfaces the nearest E-series alternative and lets you apply it in one click.
4
Live visual resistor
A purely CSS component re-renders the band colors on every change — no canvas, no SVG — so you can visually confirm the band pattern before reading a physical component or ordering parts.