Electrical & Electronics
Resistor Color Code & SMD Decoder
Decode 4, 5 or 6 resistor bands and SMD markings, or turn a resistance value into a color code.
Your inputs
Examples: 472, 1001, 4R7, R47, 01C. EIA-96 codes use a number from 01 to 96 and a multiplier letter.
Your results
Nominal resistance
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- Tolerance
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- Temperature coefficient
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- Minimum
- —
- Maximum
- —
—Colors do not specify power rating. Reverse lookup rounds to two or three significant digits. The sixth band is read as a temperature coefficient; manufacturer-specific codes may differ.
Color code reference
| Color bands | Digit | Multiplier | Tolerance | Temperature coefficient · ppm/°C |
|---|
Read resistor bands and supported SMD markings
Translate color bands or supported surface-mount markings into nominal resistance. Color mode also shows the selected tolerance range and an optional temperature coefficient. Reverse mode produces a representable band sequence for an entered resistance. The calculator interprets the selected convention; it does not identify a component's manufacturer or power rating.
Step by step
- Choose color bands, SMD code or resistance-to-bands mode. For band modes, select a 4-, 5- or 6-band format before entering the marking or requested resistance.
- In color mode, enter the significant digits in reading order, then the multiplier and tolerance. In 6-band mode, also select the temperature coefficient. In SMD mode, type the complete marking without spaces.
- Review resistance, the formula and the diagram. For color modes, compare the minimum and maximum values as well as the nominal value; print the interpretation if needed.
Settings and limits
- Band count
- A 4-band resistor uses two significant digits; 5- and 6-band formats use three. The multiplier scales those digits, the next band indicates tolerance, and the extra band in the 6-band format supplies the temperature coefficient.
- SMD conventions
- Supported markings include three- or four-digit numeric codes, EIA-96 codes such as 01A, and decimal-letter forms such as 4R7 or 4K7. All-zero numeric markings represent zero ohms. SMD mode does not infer a tolerance or temperature coefficient.
- Reverse mode and precision
- Reverse mode rounds to the nearest resistance representable by the selected digit count and multiplier. It does not choose an E-series stock value. Tolerance and temperature coefficient remain your selections; the displayed coefficient is not used to correct resistance for temperature.
Worked example
Choose 4 bands: yellow, violet, red and gold. The first two bands give 47, red multiplies by 100, and gold selects ±5% tolerance.
| R | ± | Rmin | Rmax |
|---|---|---|---|
| 4700 Ω | 5% | 4465 Ω | 4935 Ω |
Nominal resistance is 4700 Ω, or 4.7 kΩ, with a range from 4465 Ω to 4935 Ω. In SMD mode, 472 also decodes to 4700 Ω because 47 × 10² = 4700; that marking alone does not provide a tolerance in this calculator.
Questions and troubleshooting
What if I am unsure which way to read the bands?
The calculator assumes the order you enter is correct. Check the actual marking, band spacing and component documentation before relying on the result. Use the displayed sequence and reference table to catch a misplaced digit or multiplier.
Why does a measurement differ from the nominal value?
The nominal value is the marking's target resistance, while the selected tolerance defines the displayed range. The calculator does not simulate measurement conditions or temperature changes. Check the actual part specification and measurement setup.
Why is an SMD marking rejected?
A marking must match a supported syntax and, for EIA-96, a valid index and multiplier letter. Manufacturer-specific markings may use another convention. Check the code and component documentation rather than forcing an unsupported marking into numeric mode.