SMD Resistor Code
Decode 3-digit, 4-digit, and EIA-96 surface mount resistor codes.
How it works
Surface Mount Device (SMD) resistors are too small for color bands, so they use printed alphanumeric codes.
3-Digit System (Standard 5% Tolerance)
First two digits are the value, the third digit is the multiplier (number of zeros).
Example: 472 = 47 × 100 = 4.7kΩ
4-Digit System (Precision 1% Tolerance)
First three digits are the value, the fourth digit is the multiplier.
Example: 4702 = 470 × 100 = 47kΩ
EIA-96 System (Compact 1% Tolerance)
Used on smaller packages (like 0603). Consists of two numbers indicating a base value from a lookup table, followed by a letter indicating the multiplier.
Example: 01C = 100 × 100 = 10kΩ
Worked example
If you see a resistor marked 4R7:
The letter 'R' acts as a decimal point.
So, 4R7 = 4.7 Ω.
If you see 1M0:
The letter 'M' means Mega-ohms and acts as a decimal point.
So, 1M0 = 1.0 MΩ = 1,000,000 Ω.
Frequently Asked Questions
What does '000' or '0' mean?
These are zero-ohm links, effectively used as jumper wires to cross over traces on a PCB.
Are there other letters used in multipliers?
In EIA-96, letters like Z, Y, R, X, S, A, B, C, D, E, F are used as multipliers. Outside of EIA-96, 'R' indicates Ohms, 'K' indicates kilo-ohms, and 'M' indicates mega-ohms (usually acting as the decimal point).
Sources
- EIA-96 Standard.
Results are for engineering assistance. Verify important calculations and check official datasheets. See the Engineering Disclaimer.