SMD Resistor & Capacitor Code Calculator
SMD Code Decoder
Decode surface-mount resistor (3-digit, 4-digit, EIA-96) and ceramic capacitor markings instantly.
Complete Guide to SMD Resistor & Capacitor Markings
Surface-Mount Devices (SMD) are notoriously difficult to read with the naked eye due to their tiny footprints—such as 0805, 0603, or 0402 packages. While traditional axial components use colored bands, SMD components rely on condensed numerical and alphanumeric codes printed directly on the ceramic or resistive element. Use this guide alongside our free online SMD Code Calculator above to decode surface-mount components instantly.
1. Standard 3-Digit and 4-Digit Resistor Codes
Standard SMD resistors typically use 3-digit or 4-digit numerical marking systems to indicate resistance values in Ohms (Ω):
- 3-Digit Code (5% Tolerance): The first two digits represent the significant numerical digits, while the third digit is the multiplier (the number of zeros to add).
Example:472= 47 × 102 = 4,700 Ω (4.7 kΩ). - 4-Digit Code (1% High-Precision): The first three digits are significant, and the fourth digit is the multiplier.
Example:1002= 100 × 102 = 10,000 Ω (10 kΩ). - The 'R' Decimal System: For values under 10 Ω, the letter 'R' acts as the decimal point.
Example:4R7= 4.7 Ω |R050= 0.050 Ω (50 mΩ).
2. EIA-96 Code System (1% Precision 0603 Resistors)
Because 0603-sized precision resistors are too small for a 4-digit code, manufacturers use the EIA-96 standard. It consists of a 2-digit number lookup code followed by a single letter representing the multiplier.
| Multiplier Letter | Factor | Example Code | Decoded Resistance |
|---|---|---|---|
| Z / Y | 0.001 ÷ 0.01 | 01Y |
100 × 0.01 = 1 Ω |
| X or A | 0.1 ÷ 1 | 01A |
100 × 1 = 100 Ω |
| B or C | 10 ÷ 100 | 01B |
100 × 10 = 1,000 Ω (1 kΩ) |
| D or E | 1,000 ÷ 10,000 | 01D |
100 × 1,000 = 100 kΩ |
3. How to Read Ceramic SMD Capacitor Codes
Multilayer Ceramic Capacitors (MLCC) are often unlabelled on modern PCBs. However, when printed, they typically use a 3-character system representing capacitance in Picofarads (pF):
- The base unit is always in pF.
- First two digits = base value.
- Third digit = multiplier (10n).
- Example:
104= 10 × 104 pF = 100,000 pF = 100 nF or 0.1 μF. - Example:
475= 47 × 105 pF = 4,700,000 pF = 4.7 μF.
Pro Tip for Bench Technicians: Always double-check your decoded value with an LCR meter or digital multimeter out-of-circuit when diagnosing shorted or degraded surface-mount power rails!
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