SMD Resistor Code Calculator
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SMD resistors differ from conventional through-hole components in that they do not have color stripes on their housing. Instead, a special numerical or letter marking is applied to the component's surface, which identifies the part's value. Due to the small size of the housings, manufacturers use several different marking options, so manually decoding the code is not always convenient.
The most common three-digit marking is used for resistors in the standard E24 series with a tolerance of approximately ±5%. The first two digits indicate the resistance value, and the third indicates the power by which the resulting number should be multiplied. For example, the marking 472 is deciphered as 47 × 10², which corresponds to a resistance of 4700 ohms or 4.7 kOhm.
For more precise components, a four-digit code is used. This option is common among resistors in the E96 series with a tolerance of ±1%. In this case, the first three characters are the significant digits, and the last digit indicates the multiplier. For example, the designation 4701 means 470 × 10¹ = 4700 ohms.
A separate marking option is the EIA-96 system, which is used for precision SMD resistors. The two digits in the code correspond to a value from a special table, and the letter following them indicates the multiplier. For example, the designation 01C corresponds to a resistance of 100 ohms.
In some cases, the letter R is used instead of a decimal point. This method helps avoid errors when marking small packages. For example, the code 4R7 means 4.7 ohms, and R47 means 0.47 ohms.
The marking 000 or 0000 is found on jumper resistors. These elements have virtually zero resistance and are used on printed circuit boards to connect sections of a circuit.
The SMD resistor calculator allows you to quickly determine the value based on the code or, conversely, select the appropriate marking for a known resistance. This is convenient for electronics repair, component inspection, and matching parts.