SMD Resistor Code Decoder

What are SMD resistor codes?

Surface-mount device (SMD) resistors use printed numeric codes instead of color bands. The most common system uses three or four digits: in a three-digit code, the first two digits are significant figures and the third is the multiplier (number of zeros). So 472 means 4,700 ohms (4.7K). The four-digit code adds a third significant digit for higher precision: 4702 = 47,000 ohms (47K).

SMD resistors also use the EIA-96 system for high-precision (1%) components. This uses a two-digit number followed by a letter. The number represents a value from a lookup table, and the letter indicates the multiplier. For example, 01A = 100 ohms, 68C = 499K ohms.

Code systems explained

• 3-digit: Two significant digits plus multiplier. 103 = 10,000 ohms (10K). 5% tolerance.
• 4-digit: Three significant digits plus multiplier. 1002 = 10,000 ohms (10K). 1% tolerance.
• EIA-96: Two-digit code plus letter multiplier. Used for 1% precision resistors.
• R notation: The letter R indicates the decimal point. 4R7 = 4.7 ohms. Used for values under 10 ohms.

How to use this tool

Enter the code printed on the SMD resistor. The tool automatically detects whether it is a 3-digit, 4-digit, or EIA-96 code and displays the resistance value. You can also enter a resistance value to find the corresponding SMD code.

SMD package sizes

SMD resistors come in standardized package sizes identified by four-digit codes representing length and width in hundredths of an inch. Common sizes include 0402 (1.0 x 0.5mm), 0603 (1.6 x 0.8mm), 0805 (2.0 x 1.25mm), and 1206 (3.2 x 1.6mm). Smaller packages are harder to solder by hand but allow denser PCB layouts.

Worked example

Decode the SMD marking 472. In the three-digit code the first two digits are significant figures and the third is the number of zeros, so 472 means 47 followed by two zeros: 4,700 Ω, or 4.7 kΩ. A marking of 4R7 instead uses the R as a decimal point, meaning 4.7 Ω, a very different value.

Common mistakes

A common mistake is reading the R-notation as an ordinary digit; 4R7 is 4.7 Ω, not 4700 Ω. Another is applying the three-digit rule to a four-digit code, where three digits are significant and the fourth is the multiplier, so 4701 is 4,700 Ω. The EIA-96 code uses two digits plus a letter and needs a lookup table, not the zero-counting rule.

Frequently asked questions

What does 0R0 or 000 mean on an SMD resistor?

The code 000 or 0R0 indicates a zero-ohm resistor, also called a jumper. It is essentially a wire link in an SMD package, used to bridge traces on a PCB. Zero-ohm resistors are placed by the same pick-and-place machines that handle other SMD components, which is more efficient than adding a wire jumper.

How do I read the code if the resistor is too small to see?

For very small packages (0402 and below), you typically need magnification — a loupe, microscope, or high-resolution camera. In practice, most engineers identify SMD components by their PCB position and reference designator in the schematic rather than reading codes off individual components. If the component is removed from the board, a multimeter is the most reliable identification method.

What is the EIA-96 code on tiny precision resistors?

EIA-96 marks 1% resistors with two digits and a letter, for example 01A. The two digits index a lookup table of significant figures (01 means 100), and the letter is a multiplier (A means ×1). This packs precise values onto parts too small for the usual three- or four-digit codes.