SMD Capacitor Code Calculator
3/4 digit and EIA-198 capacitor markings
Required Parameters
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Quick Answer
SMD capacitor codes are in picofarads: the last digit is the multiplier (number of zeros). 104 = 100,000 pF = 100 nF = 0.1 µF. EIA-198 codes use a letter-digit-letter format for 1% precision parts.
SMD Capacitor Code Calculator
Decode the markings on surface-mount capacitors. SMD capacitors use numeric codes to represent capacitance values in picofarads.
3-Digit Code System
First two digits are significant figures, third digit is the multiplier (number of zeros).
- 104 = 10 x 10^4 pF = 100 nF
- 473 = 47 x 10^3 pF = 47 nF
- 222 = 22 x 10^2 pF = 2.2 nF
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Design Notes
Most SMD ceramic capacitors (MLCCs) are unmarked. When marked, digit codes give capacitance in picofarads. The biggest practical concern is not the marking but the dielectric type: C0G/NP0 ceramics are stable but limited to small values, while X7R and X5R offer high capacitance but lose value with DC bias and temperature.
Common Mistakes
- 1
Assuming an unmarked SMD component is a capacitor — it could be a resistor, inductor, or even a diode in some packages.
- 2
Forgetting that MLCC capacitance drops significantly under DC bias (X5R 10µF at 10V may only be 3-4µF with 8V applied).
- 3
Using Y5V/Z5U dielectrics where stable capacitance is needed — their value can change by 80% with temperature.
Engineering Handbox
1. First two digits: 10 (significant figures in pF) 2. Last digit: 4 (add four zeros) 3. Raw: 10 + 0000 = 100,000 pF 4. Convert: 100,000 pF = 100 nF = 0.1 µF
Knowledge Base
What unit is the SMD capacitor code in?
Digit codes are in picofarads (pF). The last digit is the multiplier (number of zeros). Example: 104 = 10 + 0000 = 100,000 pF = 100 nF = 0.1 µF. 473 = 47 + 000 = 47,000 pF = 47 nF. 220 = 22 pF (no zeros added).
What is the EIA-198 capacitor code system?
EIA-198 uses a letter-digit-letter format for 1% precision capacitors. The first letter indicates the base value from a lookup table, the digit is the multiplier (power of 10), and the optional third letter indicates tolerance. Example: A5J = 1.0 pF × 10^5 = 100,000 pF = 100 nF, J = 5% tolerance.
How do I convert between pF, nF, and µF?
1 µF = 1,000 nF = 1,000,000 pF. Common conversions: 100 nF = 0.1 µF = 100,000 pF (code 104). 10 nF = 0.01 µF = 10,000 pF (code 103). 1 nF = 0.001 µF = 1,000 pF (code 102). 100 pF (code 101).
What do the tolerance letters on capacitors mean?
Common tolerance codes: B = ±0.1 pF, C = ±0.25 pF, D = ±0.5 pF, F = ±1%, G = ±2%, J = ±5%, K = ±10%, M = ±20%, Z = +80%/-20%. For precision applications, use C0G/NP0 caps with J (5%) or better tolerance.
What is the most common SMD capacitor code?
104 (100 nF / 0.1 µF) is by far the most common — it is the standard decoupling capacitor placed on virtually every IC power pin. Other common codes: 105 (1 µF), 106 (10 µF), 103 (10 nF), 102 (1 nF).
Why does my SMD capacitor not have any markings?
Most MLCC (Multi-Layer Ceramic Capacitor) SMD capacitors are unmarked because they are too small. Unlike resistors which usually have markings on 0402 and larger, capacitors are rarely marked at any size. Identify them from the BOM, schematic, or by measuring with an LCR meter.
What is the difference between ceramic capacitor dielectric types?
C0G/NP0: ultra-stable, no voltage/temp dependence, tiny capacitance (up to ~10 nF). X7R: stable enough for most uses, ±15% tolerance, slight capacitance loss with DC bias. Y5V/Z5U: cheapest, but capacitance drops by 50-80% with temperature and applied voltage — avoid for precision circuits.
How does DC bias affect ceramic capacitor value?
Class II/III ceramics (X7R, X5R, Y5V) lose capacitance when DC voltage is applied. A 10µF 0805 X5R capacitor rated at 10V might only provide 3-4µF when 8V is applied. This is the most underappreciated problem in capacitor selection. Always check the manufacturer's DC bias curves.
What does the R code mean in capacitor markings?
Like resistors, R indicates the decimal point. 1R5 = 1.5 pF, 2R2 = 2.2 pF. These are used for very small capacitance values below 10 pF, commonly found in RF circuits, impedance matching networks, and crystal oscillator load capacitors.
What capacitor voltage rating codes are used on SMD parts?
When marked, voltage codes typically follow the EIA standard: 0G = 4V, 0J = 6.3V, 1A = 10V, 1C = 16V, 1E = 25V, 1H = 50V, 1J = 63V, 2A = 100V, 2D = 200V, 2E = 250V. Most consumer electronics use 10V-25V rated capacitors for 3.3V/5V circuits.
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