SMD resistors

1.1k

All surface mount resistors have a 3-digit or 4-digit code.

Here is a picture of a 3-digit surface mount resistor

 

The first and second figures indicate the significant figures and the third one, is the multiplier. As an example, if the SMD resistor has the figures 102, it indicates 1, 0 = 10 x 102 ohms. That is the value is 1K. This next example can catch people out at first , 100 is not in fact a 100 ohm resistor but is in fact a 10×100 = 10 ohms or 10×1 = 10 ohms. In the case of resistors less than 10 ohms, the letter R is used in the position of decimal. For example, 4R7 represents 4.7 Ohms.

3-digit code examples:

330 = 33 × 100 (1) = 33Ω
331 = 33 × 101 (10) = 330Ω
332 = 33 × 102 (100) = 3300Ω or 3k3
3R3 = 3.3Ω

4-Digit markings are used to denote high tolerance SMD resistors. In these resistors, the first, second and third figures represent the significant values while the fourth is the multiplier. For example, if the figures are 3302 then the value is 330 x 102 ohms or 33K. In 4 figure marking, the values less than 100 ohms use the letter R at the position of the decimal point.

4-digit code examples:

3300 = 330 × 100 (1) = 330Ω
3301 = 330 × 101 (10) = 3300Ω or 3k3Ω
3302 = 330 × 102 (100) = 33000Ω or 33KΩ
33R0 = 33.0Ω

EIA 96 marking system is used in resistors with 1% tolerance. In this marking scheme the first and second digits indicate the resistor value and the third character is a letter that indicates the multiplier. This scheme can be hard to get used to at first.

Here is a table to help with the first 2 digits

 

Here is the multiplier

Lets look at some examples

01C = 10kΩ (100×100)
01B = 1kΩ (100×10)
01D = 100kΩ