SMD resistors use printed characters rather than the colored bands used by through-hole parts. This overview separates the three-digit, four-digit, R-decimal, zero-ohm, and EIA-96-style code systems so the printed mark is read in the right context. Use the SMD Resistor Code Decoder for the marking on a chip resistor; the through-hole color calculator is a different tool and should not be used as the SMD lookup.
Identify the marking system first
| Format | Example | Basic rule | Typical use |
|---|---|---|---|
| 3-digit | 103 | 10 x 10^3 = 10 kohm | Common nominal values |
| 4-digit | 1002 | 100 x 10^2 = 10 kohm | Higher precision marking |
| R notation | 4R7 | R marks the decimal point | Low-ohm and decimal values |
| EIA-96 style | 01C | Index table plus multiplier letter | Precision SMD resistors |
Three-digit and four-digit codes
In a common three-digit system, the first two characters are significant digits and the third digit is the number of zeroes. 103 therefore means 10,000 ohms, or 10 kohm. A four-digit code uses the first three characters as significant digits and the fourth as the multiplier, so 1002 means 10,000 ohms. This convention can vary by manufacturer, especially on very small or specialized parts.
R notation for decimal values
The letter R acts as the decimal point. 4R7 means 4.7 ohms, 0R22 means 0.22 ohms, and R010 means 0.010 ohms in systems that print leading R notation. Never remove the R and treat it as a multiplier. Low-ohm shunts often need additional power, current, and Kelvin-layout information that the code cannot supply.
EIA-96 needs a reference table
EIA-96-style marks combine a two-digit index with a multiplier letter. The index points to a preferred resistance value and the letter supplies the power-of-ten multiplier. A code such as 01C cannot be decoded from the characters alone without the correct EIA-96 table and letter mapping. Package size, top mark orientation, and manufacturer documentation are important cross-checks.
Examples and common misreads
| Printed mark | Likely meaning | Do not assume |
|---|---|---|
| 103 | 10 kohm in a common 3-digit system | 103 ohms |
| 1002 | 10 kohm in a common 4-digit system | 1,002 ohms |
| 4R7 | 4.7 ohms | 47 ohms |
| 0R22 | 0.22 ohms | 22 ohms |
| R010 | 0.010 ohms | 10 ohms |
| 01C | EIA-96-style candidate | Decode without the correct table |
Why a single lookup answer can be unsafe
Top marks may be reused across product families, and a tiny character can be read incorrectly as 0, O, 1, I, 5, or S. Confirm the package, board reference, manufacturer, and datasheet. A lookup can suggest a candidate value, but it cannot confirm the resistor wattage, voltage, temperature coefficient, pulse rating, or authenticity. For a low-ohm shunt, current rating and layout may matter more than the printed resistance alone.
Frequently asked questions
Can the through-hole color calculator decode 103?
No. 103 is a printed SMD marking and uses a different code system. Use the SMD Resistor Code Decoder instead.
Is 4R7 the same as 47?
No. In R notation, R marks the decimal point, so 4R7 means 4.7 ohms.
Can 01C be decoded from memory?
Use the correct EIA-96 table and verify the manufacturer series, package, and datasheet.
Source and limits
This guide is limited to reading a printed SMD resistor marking and identifying the code system represented by that marking. It uses the SMD conventions represented by the site decoder, including the documented examples and the EIA-96-style table workflow. It does not treat an SMD mark as a through-hole color-band code.
- Use the SMD Resistor Code Decoder as a reading aid, then verify the tolerance, specification, package, and manufacturer marking against the product series datasheet.
- A printed code alone does not establish power rating, voltage rating, temperature coefficient, pulse behavior, current capability, authenticity, or suitability for replacement.
- If the package, character, code system, or manufacturer is uncertain, keep the result as a candidate and return to the product series datasheet before making a safety, procurement, or compliance decision.
Related guides
3-Digit SMD Codes explains the first code family; 4-Digit SMD Codes covers the longer marking; and R Notation explains decimal values.