Ceramic Capacitor Code Calculator: How to Read

This calculator decodes the three- or four-digit code printed on ceramic capacitors, returning the capacitance value in picofarads (pF), microfarads (µF), and nanofarads (nF). You enter the numeric code (e.g., 104, 223, 475) and the calculator gives you the capacitance and the working voltage if you also provide that code. The result is the actual capacitance value that the code represents, using the standard EIA-198 marking scheme.

Formula

The code on a ceramic capacitor is read as: first two digits are the significant figures, third digit is the multiplier (power of 10) in picofarads. For a three-digit code ABC, the capacitance is:

C (pF) = (10 × A + B) × 10^C

For a four-digit code ABCD, the first three digits are significant and the fourth is the multiplier: C (pF) = (100 × A + 10 × B + C) × 10^D

Where: A, B, C, D are digits 0–9. The result is in picofarads (pF). To convert: 1,000 pF = 1 nF; 1,000,000 pF = 1 µF. For example, code 104 means 10 × 10⁴ pF = 100,000 pF = 100 nF = 0.1 µF.

Worked Example

Using the default code 104:

1. First two digits: 10 (significant figures)
2. Third digit: 4 (multiplier)
3. Calculate: 10 × 10⁴ = 10 × 10,000 = 100,000 pF
4. Convert: 100,000 pF ÷ 1,000 = 100 nF; 100,000 pF ÷ 1,000,000 = 0.1 µF

The calculator returns 100000 pF, 0.100000 µF, and 100.000 nF.

How Ceramic Capacitor Codes Work

Ceramic capacitors are small, so manufacturers print a short code instead of the full value. The most common system is the EIA-198 three-digit code. The first two digits are the value in picofarads, and the third digit is the number of zeros to add. For example, 223 means 22 × 10³ pF = 22,000 pF = 22 nF. Codes with four digits (e.g., 1004) follow the same logic: first three digits are the value, fourth is the number of zeros. A code of 1004 means 100 × 10⁴ pF = 1,000,000 pF = 1 µF.

Sometimes you see a letter after the code (e.g., 104K). The letter indicates tolerance: J = ±5%, K = ±10%, M = ±20%. This letter is not part of the capacitance value. Also, some capacitors use a different marking for very small values, like a single digit or a letter (e.g., “1� means 1 pF, “R� can indicate a decimal point, as in “4R7� = 4.7 pF).

How to Use the Calculator

1. Find the code printed on the capacitor. It is usually three or four digits, sometimes with a letter.
2. Enter the numeric digits only (ignore any letter).
3. Press calculate. The result shows the capacitance in pF, nF, and µF.

If the code has a letter like “K� or “M�, that is tolerance, not capacitance. If the code is something like “0.1� or “.1�, it is already in µF and you don’t need the calculator. If the code is two digits or less, it is usually in pF directly (e.g., “10� = 10 pF).

Common Mistakes and Misconceptions

• Misreading the third digit as a value, not a multiplier: 104 is not 104 pF; it is 100,000 pF.
• Ignoring tolerance letters: The letter after the code is not part of the value.
• Assuming all codes are in pF: Some codes like “0.1� are in µF, and some like “100� are in pF (100 pF).
• Confusing nF and µF: 1 µF = 1,000 nF, so 0.1 µF is 100 nF, not 10 nF.
• Using the code for voltage: The voltage rating is often printed separately (e.g., “50V� or “16V�). The numeric code only gives capacitance.

When to Use This Calculator vs. a Multimeter

This calculator is for reading the printed code. If the code is faded or missing, you cannot use the calculator. In that case, you need a multimeter with capacitance measurement. However, a multimeter measures the actual capacitance, which may differ from the marked value due to tolerance (e.g., ±10%). The calculator gives the nominal value, which is what the capacitor is designed to be. For circuit design, use the nominal value; for troubleshooting, measure with a meter.

Limitations of the Code System

The EIA-198 code works for most ceramic capacitors, but there are exceptions. Some capacitors use a different scheme, such as the “R� notation for decimal points (e.g., “4R7� = 4.7 pF) or a direct marking in µF (e.g., “0.1� or “1u�). Also, some high-voltage ceramic capacitors use a code that includes the voltage rating, like “2A104� where “2A� is a voltage code (100V). In such cases, the first two characters are voltage, and the last three are capacitance. This calculator does not decode voltage codes; it only handles the capacitance part. Always check the datasheet if you are unsure.

Frequently Asked Questions

What does 104 mean on a ceramic capacitor?

104 means 10 × 10⁴ pF, which is 100,000 pF, or 100 nF, or 0.1 µF. It is one of the most common capacitor values used in electronics.

How do I convert pF to µF?

Divide by 1,000,000. For example, 100,000 pF ÷ 1,000,000 = 0.1 µF. To convert nF to µF, divide by 1,000.

What does the letter at the end of the code mean?

The letter indicates tolerance: J = ±5%, K = ±10%, M = ±20%. It does not affect the capacitance value. For example, 104K is a 100 nF capacitor with ±10% tolerance.

Can I use this calculator for polyester or film capacitors?

Yes, many film capacitors use the same three-digit code. However, some film capacitors are marked directly in µF (e.g., “0.47�). If the code is numeric, the same rules apply.

Why does my capacitor have a code like “0.1� or “.1�?

That is a direct marking in microfarads. “0.1� means 0.1 µF, which is 100 nF. No decoding needed.

What if the code has four digits?

Use the first three digits as the value and the fourth as the multiplier. For example, 1004 means 100 × 10⁴ pF = 1,000,000 pF = 1 µF.

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in code | Capacitor Code | - | 104 | 0
out pF | Capacitance (pF) | pF | (floor(code / 100) * 10^(code % 100)) | 0
out uF | Capacitance (µF) | µF | (floor(code / 100) * 10^(code % 100)) / 1000000 | 6
out nF | Capacitance (nF) | nF | (floor(code / 100) * 10^(code % 100)) / 1000 | 3