A three-digit SMD resistor code is a compact printed marking that normally uses two significant digits followed by a multiplier digit. This page is for the specific question: how do you read marks such as 103 and 220? Start with the SMD Resistor Code Decoder, then check that the component and product series use this code system before treating the result as a candidate value.
Separate the two parts of the code
Read the marking from left to right as two value digits and one multiplier digit. The first two characters provide the significant part of the nominal resistance. The last character tells the decoder how many zeroes or powers of ten to apply. The characters are therefore a code-system instruction, not a decimal number to read as 103 ohms or 220 ohms.
Worked example: 103
For 103, the first two digits are 10 and the final digit is 3. In the supported three-digit rule, that gives 10 x 10^3 ohms, or 10 kohm. The important reading step is to keep the final 3 in the multiplier position. Entering the full printed mark in the decoder keeps the code together and returns the decoded summary with the code-system detail.
Worked example: 220
For 220, the first two digits are 22 and the final digit is 0. The supported result is 22 x 10^0 ohms, or 22 ohms. Do not read the mark as a four-digit value, and do not add an extra zero simply because the marking has three characters. The position of the final digit controls the interpretation.
What this format does not tell you
| Printed information | What the decoder can read | What still needs verification |
|---|---|---|
| 103 | Three-digit code result: 10 kohm | Tolerance, package, specification, and manufacturer series |
| 220 | Three-digit code result: 22 ohm | Whether the part is the intended product and rating |
The marking is only the printed resistance code. It does not by itself establish tolerance, power rating, voltage rating, temperature coefficient, pulse behavior, or replacement suitability. Those details belong to the product series datasheet and the component documentation.
Check the code before choosing a next step
Use the number of printed characters and the package context as evidence, but do not force every three-character mark into this format. A mark can belong to another code system, or a tiny character can be difficult to distinguish. If the code system or package is uncertain, keep the decoder result as a candidate and compare the physical part with the product series datasheet. The 4-Digit SMD Resistor Code guide is the next step when the marking has four characters; the R notation guide covers a visible R instead of a final multiplier digit.
Source and limits
This page covers only the supported three-digit printed SMD marking rule represented by the site decoder. The examples are limited to 103 and 220 and are shown as code-system readings, not as a substitute for part identification.
- Use the SMD Resistor Code Decoder for the printed marking, then return to the product series datasheet for tolerance, specification, package, and manufacturer verification.
- Do not treat an SMD printed mark as a through-hole color-band code or use the through-hole color calculator for this page.
- A code-only result is not a safety, procurement, compliance, or replacement decision.