Surface Mount Decoding

SMD Resistor Code Calculator (3-Digit, 4-Digit, EIA-96)

PCB reverse engineering, smartphone and laptop motherboard micro-soldering. Decodes surface mount resistor markings into exact resistance values with tolerance ratings.

SMD Resistor Code Calculator (3-Digit, 4-Digit, EIA-96)
Code Digits
Calculated Result
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Instant Calculation
Engineering Output
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Auxiliary Output
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Step-by-Step Derivation ▼ Show Steps
Governing Formula Verified Physics
3-Digit: (AB) × 10^C  |  4-Digit: (ABC) × 10^D  |  'R' denotes decimal point

Calculations adhere to standard electrical engineering physics and National Electrical Code (NFPA 70) regulations.

Engineering Principles & Calculations

This calculator uses the exact mathematical relationships between SMD Code String (e.g. '472', '1001', '01A', 'R050') to determine Resistance Value (Ohms / Kilohms / Milliohms), Tolerance (1% or 5%). In practical installations, factors such as ambient raceway temperature, harmonic distortion, duty cycle continuous operation, and conductor impedance must be accounted for by a certified electrician.

Decodes surface mount resistor markings into exact resistance values with tolerance ratings.

Typical Application & Industry Guidelines

PCB reverse engineering, smartphone and laptop motherboard micro-soldering.

Reference Matrix

SMD Resistor Code Calculator (3-Digit, 4-Digit, EIA-96) Benchmark Lookup Table

SMD MarkingDecoded OhmsToleranceApplication
1021,000 Ohms (1 kOhm)± 5%Standard Pull-up
4724,700 Ohms (4.7 kOhm)± 5%I2C Bus Pull-up
10310,000 Ohms (10 kOhm)± 5%Microcontroller Reset
10011,000 Ohms (1 kOhm)± 1%Precision Voltage Divider
470247,000 Ohms (47 kOhm)± 1%Audio Op-Amp Feedback
R0500.050 Ohms (50 mOhm)± 1%Current Sensing Shunt
FAQ

Frequently Asked Questions

What does the letter 'R' mean in an SMD code? +
The letter 'R' serves as a decimal point for fractional Ohm values. For example, 4R7 = 4.7 Ohms; 0R22 = 0.22 Ohms; R050 = 0.050 Ohms (50 milliohms).
What is the difference between 3-digit and 4-digit SMD codes? +
3-digit codes indicate standard 5% tolerance resistors (2 significant digits + multiplier). 4-digit codes indicate 1% precision resistors (3 significant digits + multiplier).
What is the EIA-96 SMD coding system? +
EIA-96 is a 2-digit number (referencing a lookup table) followed by a letter multiplier, used on small 0603 packages for 1% resistors (e.g. 01A = 100 Ohms).

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