Surface Mount Device (SMD) resistors are the backbone of modern embedded hardware. Because they are too small for traditional color bands, manufacturers print alphanumeric codes on the top of the package to indicate their resistance value.

The Three SMD Coding Systems

Reading an SMD resistor isn't always straightforward because the industry uses three distinct coding systems depending on the size and precision of the component:

• 3-Digit & 4-Digit Systems: Used for 5% and 1% tolerance resistors respectively. The first digits are the significant figures, and the final digit is the multiplier (power of 10). The letters 'R' and 'M' are used as decimal points for Ohms and Milliohms (e.g., 4R7 = $4.7\Omega$).
• EIA-96 System: Found on tiny 0603 packages (1% tolerance). It uses two digits to look up a base value from the standard E96 table, followed by a letter that dictates the multiplier (e.g., 01C = $10\text{ k}\Omega$).

Note: Larger packages (like current-sense resistors) may append a specific EIA tolerance letter to the end of the code (e.g., F = 1%, J = 5%).

Use the interactive tool below to enter any SMD code you see on your PCB. The engine will automatically detect the standard being used, decode the multiplier, handle explicit tolerance letters, and give you the exact resistance value.

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