SMD Capacitor Code Calculator & How to Read Values

This SMD capacitor code calculator decodes the three- or four-digit markings printed on surface-mount ceramic capacitors and returns the capacitance value in picofarads (pF), nanofarads (nF), and microfarads (µF). You enter the code (e.g., 104, 223, or 475) and the calculator gives you the capacitance in all three common units, plus the equivalent EIA-96 code if you select that option. The calculator also handles the EIA-96 system for high-precision capacitors, where a two-digit code plus a letter (e.g., 01A, 68C) encodes a specific value and multiplier.

Formula

The standard formula for a 3-digit SMD capacitor code is:

C (pF) = (first digit)(second digit) × 10^{third digit}

For a 4-digit code, the first three digits are the significant figures and the fourth digit is the multiplier:

C (pF) = (first three digits) × 10^{fourth digit}

For the EIA-96 system, the two digits map to a base value from a standard table (e.g., 01 = 100, 02 = 102, 03 = 105, … 96 = 976) and the letter indicates the multiplier (A = 10⁰, B = 10¹, C = 10², D = 10³, E = 10⁴, F = 10⁵, R = 10^-1, S = 10^-2, T = 10^-3, U = 10^-4, V = 10^-5, W = 10^-6).

Worked Example

Using the default code 104 (3-digit system):

1. First digit = 1, second digit = 0, third digit (multiplier) = 4
2. Value = 10 × 10⁴ = 10 × 10,000 = 100,000 pF
3. Convert to nF: 100,000 pF ÷ 1000 = 100 nF
4. Convert to µF: 100,000 pF ÷ 1,000,000 = 0.1 µF

The calculator returns 100,000 pF, 100 nF, and 0.1 µF for the code 104.

How SMD Capacitor Codes Work

Surface-mount ceramic capacitors are too small to print full values, so manufacturers use a shorthand. The most common is the 3-digit code, where the first two digits are the significant figures and the third digit is the number of zeros to add (as a power of 10). The result is always in picofarads. For example, 223 means 22 × 10³ pF = 22,000 pF = 22 nF.

Larger capacitors (often in 1206 or larger packages) may use a 4-digit code, where the first three digits are the value and the fourth is the multiplier. For instance, 475 means 47 × 10⁵ pF = 4,700,000 pF = 4.7 µF.

High-precision capacitors (tolerance of 1% or 2%) use the EIA-96 system, which is the same as used for surface-mount resistors. The two digits and a letter encode a value from a lookup table. For example, 01A = 100 pF (1.00 × 10² pF), 68C = 499 × 10² pF = 49,900 pF = 49.9 nF.

How to Use the Calculator

1. Select the code system from the dropdown: 3-digit, 4-digit, or EIA-96.
2. Type the code exactly as printed on the capacitor (e.g., 104, 475, 01A).
3. Click Calculate.
4. Read the capacitance in pF, nF, and µF.

The calculator assumes the code is for a ceramic capacitor. For tantalum capacitors, the marking may include a polarity stripe and a different code format (e.g., a letter for the voltage rating). This calculator only decodes the capacitance value, not voltage or tolerance.

Common Mistakes and Pitfalls

• Misreading the third digit: A common error is to read 104 as 104 pF instead of 100,000 pF. Always remember the third digit is the multiplier, not part of the value.
• Unit confusion: The base unit is always picofarads. A code like 103 gives 10,000 pF, which is 10 nF, not 10 µF.
• EIA-96 vs. 3-digit: A code like 01A is not a 3-digit code; it’s EIA-96. Using the 3-digit rule would give 0 pF, which is wrong.
• Capacitor tolerance: The code does not indicate tolerance. A 104Z capacitor has a tolerance of +80%/-20%, while a 104F is ±1%. Always check the datasheet for tolerance.
• Voltage rating: The capacitance code does not tell you the voltage rating. Two capacitors with the same code may have different maximum voltages.

When to Use Each Code System

Use the 3-digit code for most standard ceramic capacitors (X7R, X5R, C0G) with capacitance values from 1 pF to 22 µF. The 4-digit code appears on larger capacitors, typically above 1 µF, where a 3-digit code would be ambiguous (e.g., 225 for 2.2 µF). The EIA-96 system is reserved for precision capacitors with tight tolerances (±1% or ±2%), often used in timing circuits, filters, and precision analog applications.

If you encounter a code that doesn’t match any system, it may be a proprietary marking. In that case, the only reliable way to determine the value is to measure it with an LCR meter or consult the manufacturer’s datasheet.

Alternatives and Verification

If you don’t have a calculator, you can decode manually using the formulas above. For a quick sanity check, remember that 100 pF = 0.1 nF = 0.0001 µF. A code of 101 is 100 pF, 102 is 1 nF, 103 is 10 nF, 104 is 100 nF, and 105 is 1 µF. This sequence is worth memorizing.

For physical verification, an LCR meter (inductance, capacitance, resistance) is the definitive tool. Set it to capacitance mode and measure the part. If the measured value is significantly different from the code, the capacitor may be damaged or the code may be misleading due to aging or temperature effects.

Limitations of the Code System

The code system only gives the nominal capacitance. Real capacitors have a tolerance (e.g., ±10%, ±20%) and their capacitance varies with temperature and DC bias. For example, a 104 (100 nF) X7R capacitor might measure 80 nF at 50V DC due to DC bias derating. The code does not reflect this. Also, some manufacturers use a different code for capacitors with voltage ratings above 100V, but the capacitance decoding remains the same.

Frequently Asked Questions

What does 104 mean on a capacitor?

104 is a 3-digit code. The first two digits (10) are the significant figures, and the third digit (4) is the multiplier (10⁴). So the value is 10 × 10,000 = 100,000 pF, which equals 100 nF or 0.1 µF.

How do I read a 4-digit capacitor code?

In a 4-digit code, the first three digits are the value and the fourth is the multiplier. For example, 475 means 47 × 10⁵ pF = 4,700,000 pF = 4.7 µF. The first three digits are always a three-digit number, so 100 means 10.0, not 1.00.

What is the EIA-96 code for capacitors?

EIA-96 is a system for precision capacitors (and resistors) that uses two digits and a letter. The digits correspond to a base value from a table (e.g., 01 = 100, 02 = 102, 03 = 105, … 96 = 976), and the letter gives the multiplier (A = 10⁰, B = 10¹, C = 10², etc.). For example, 01A = 100 pF, 68C = 499 × 10² pF = 49,900 pF = 49.9 nF.

Why does my capacitor have a letter at the end like 104K?

The letter after the numeric code indicates tolerance. K means ±10%, J means ±5%, M means ±20%, and F means ±1%. The capacitance value is still decoded the same way (104 = 100 nF), but the actual part may be anywhere within that tolerance range.

Can I use this calculator for tantalum capacitors?

No. Tantalum capacitors often use a different marking system that includes a polarity stripe and a code where the first digit is the value and the second is the multiplier (similar to 3-digit but sometimes without the third digit). Also, the voltage rating is usually marked separately. This calculator is designed for ceramic capacitors only.

What if my capacitor has no code at all?

Some very small capacitors (e.g., 0402 package) may have no marking due to size constraints. In that case, you cannot determine the value from the part itself. You need to refer to the bill of materials or measure it with an LCR meter.

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in code | Capacitor code (e.g., 104) | - | 104 | 0
sel type | Code system | 3-digit=1, 4-digit=2, EIA-96=3
out cap_pf | Capacitance | pF | (type==1 ? (code[0]-'0')*10^(code[1]-'0')*(10^(code[2]-'0')) : type==2 ? (code[0]-'0')*100+(code[1]-'0')*10+(code[2]-'0') : 0) | 0
out cap_nf | Capacitance | nF | cap_pf / 1000 | 3
out cap_uf | Capacitance | µF | cap_pf / 1000000 | 6