Understanding SMD capacitor markings
Unlike through-hole capacitors with printed labels, SMD ceramic capacitors often use compact numeric or alphanumeric codes to represent capacitance. These markings must be interpreted correctly to avoid assembly errors, incorrect BOM entries or mis-sized bypass and filter networks.
This calculator helps you translate common SMD capacitor codes—including 2-digit, 3-digit, and EIA standard markings—into usable capacitance values (pF, nF or µF).
How SMD capacitor codes work
Most ceramic capacitors (MLCC) use a three-digit EIA code similar to resistor markings:
Three-digit EIA format (XYZ)
- X and Y = significant digits
- Z = multiplier (power of 10 in pF)
Formula:
Capacitance (pF) = (XY) × 10Z
Example:
- Code: 104
- (10) × 10⁴ = 100,000 pF = 100 nF
Two-digit codes
Sometimes very small capacitors (especially under 10 pF) use simple two-digit values where the number is the capacitance directly in pF.
Examples:
- “1R0” → 1.0 pF
- “4R7” → 4.7 pF
- “10” → 10 pF
Capacitance prefixes
In many datasheets or packaging you will also see:
- R = decimal point (e.g., 3R3 = 3.3 pF)
- n or µ occasionally appear on larger parts
Common EIA capacitor code examples
| Code | Capacitance | SI Units |
|---|---|---|
| 101 | 100 pF | 0.1 nF |
| 102 | 1000 pF | 1 nF |
| 103 | 10,000 pF | 10 nF |
| 104 | 100,000 pF | 100 nF |
| 105 | 1,000,000 pF | 1 µF |
How to use the SMD Capacitor Code Calculator
- Enter the capacitor marking: Type any standard three-digit, two-digit or decimal (“R”) style marking into the input field.
- View decoded capacitance: The calculator shows capacitance in pF, nF and µF simultaneously.
- Apply to your design: Use the decoded value for PCB assembly, component validation, BOM entry, replacement selection or troubleshooting.
Design notes for practical use
- SMD size code does not imply capacitance: 0402, 0603, 0805 only describe package size, not value.
- Voltage rating is not printed on the part: Check the datasheet or packaging for rated voltage (V).
- Temperature characteristics matter: X7R, X5R, C0G/NP0, Y5V indicate dielectric stability and tolerance.
- High-value MLCCs derate under bias: A 10 µF MLCC may deliver far less when used at high DC bias voltages.
This calculator provides a fast way to interpret the often cryptic markings on SMD capacitors, helping engineers identify parts correctly and avoid assembly or debugging mistakes.
