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SMD Resistor
Surface-mount (SMD) resistors are tiny rectangles with the value printed as a short code. This tab decodes those codes.
The code is a very small version of the same idea as the color bands. Digits give the value and one character gives the multiplier. There are four styles.
The first two digits are the value and the third is the number of zeros to add.
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472is 47 followed by two zeros, so 4,700 Ω, or 4.7 kΩ. -
103is 10 followed by three zeros, so 10 kΩ. - Tolerance is typically ±5%.
The first three digits are the value and the fourth is the number of zeros.
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1002is 100 followed by two zeros, so 10 kΩ. - Tolerance is typically ±1%, and can be tighter on precision parts.
Precision (1%) resistors that are too small for four digits use a lookup. The two digits pick one of 96 standard values, and the letter is the multiplier.
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01C: code 01 means 100, letter C means x100, so 10,000 Ω, or 10 kΩ. -
68X: code 68 means 499, letter X means x0.1, so 49.9 Ω.
The tool includes the full table of 96 values. Open EIA-96 reference tables under the results, and tap any entry to try it.
Multiplier letters: Z = x0.001, Y or R = x0.01, X or S = x0.1, A = x1, B or H = x10, C = x100, D = x1000, E = x10000, F = x100000.
An R marks where the decimal point goes. It is common for low values.
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4R7is 4.7 Ω. -
R47is 0.47 Ω. -
10R0is 10.0 Ω.
You may also see K or M used the same way, such as 4K7 for 4.7 kΩ.
0, 000, and 0000 (and 0R0) mean a zero-ohm resistor. It is just a wire link in a resistor package, used to bridge two pads on a circuit board.
The chip picture shows your code. 01C is an EIA-96 code for 10 kΩ ±1%, with the working below.
- Click SMD Resistor.
- Type the marking in the box. The black chip picture updates to show your code.
- Read Resistance, Minimum, Maximum, Type, and Tolerance. The numbered working shows how the code was read.
An ambiguous marking like 47R shows both readings: EIA-96 (3.01 Ω) and R notation (47 Ω).
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47Ris ambiguous. It can be an EIA-96 code (3.01 Ω) or 47 Ω in R notation. The tool shows both readings. If you cannot tell, measure it. - Tolerance is an estimate. Most SMD markings do not encode tolerance. The tool gives the typical tolerance for that style and says so.
- Tiny parts have no marking. Resistors in 0402 size and smaller are often blank. Nothing can be decoded, so measure it out of circuit.
- Do not confuse with capacitors. SMD capacitors are usually unmarked, and a number on a part does not tell you what kind it is. Check the Capacitor tab if the part is not a resistor.