Ceramic Capacitor Code Calculator

Calculator Inputs

Marked code

Tolerance letter

Value for reverse code

Value unit

Voltage code

Manual rated voltage

Dielectric class

Quantity

Connection

Frequency

Frequency unit

Operating voltage

Measured value

Measured unit

Formula Used

Three digit code: capacitance in pF = first two digits × 10^{third digit}.

Four digit code: capacitance in pF = first three digits × 10^{fourth digit}.

Unit conversion: 1 nF = 1,000 pF. 1 µF = 1,000,000 pF.

Parallel: C_eq = C × quantity. Series: C_eq = C ÷ quantity for identical parts.

Reactance: X_C = 1 ÷ (2πfC). Use C in farads and f in hertz.

Energy: E = 0.5 × C × V². Charge: Q = C × V.

How to Use This Calculator

Enter the printed capacitor code, such as 104K or 472J.
Select a tolerance letter if it is not included in the marking.
Enter voltage, dielectric, quantity, and frequency details when needed.
Use the measured value fields to check a real part against tolerance.
Press calculate. The result appears above the form and below the header.
Use CSV or PDF download buttons to save the result.

Example Data Table

Marking	Decoded Value	Common Name	Tolerance Example	Typical Use
101J	100 pF	0.1 nF	±5%	RF coupling
472K	4,700 pF	4.7 nF	±10%	Signal filtering
104M	100,000 pF	100 nF	±20%	Bypass and decoupling
105K	1,000,000 pF	1 µF	±10%	Bulk bypass

Understanding Ceramic Capacitor Codes

Ceramic capacitors often use short markings because the body is small. A three digit code gives the capacitance in picofarads. The first two digits are significant figures. The third digit is the multiplier. A marking of 104 means 10 followed by four zeros pF. That equals 100,000 pF, 100 nF, or 0.1 uF.

Why Tolerance Matters

The letter after the number explains allowed variation. J means plus or minus 5 percent. K means plus or minus 10 percent. M means plus or minus 20 percent. Small value capacitors can also use absolute pF tolerances, such as B, C, or D. This calculator shows the high and low limits. Those limits help you compare a measured part with its printed mark.

Using Codes In Real Circuits

Capacitance affects filtering, timing, coupling, and bypass behavior. A larger value passes more changing current. A smaller value blocks more low frequency content. The reactance option shows this effect at your chosen frequency. It is useful for audio filters, oscillator networks, decoupling checks, and impedance estimates. Voltage rating also matters. A capacitor should normally work below its printed rating. Extra margin improves reliability.

Dielectric And Temperature Notes

Ceramic dielectrics do not behave the same way. C0G or NP0 parts are stable and suit timing or RF circuits. X7R and X5R parts offer more capacitance in small packages. Their value can shift with temperature, voltage, and aging. Y5V and Z5U parts can change much more. They are best for noncritical bypass positions, not precision networks.

Best Practice For Identification

Always read the full marking under good light. Confirm the package, voltage rating, and dielectric when the circuit is sensitive. Use a meter when parts are loose or old. Then compare the measurement with the tolerance range. This calculator gives a fast first check. It also creates a readable export for records, repair notes, and engineering reports.

Reading Unusual Markings

Some parts show R instead of a decimal point. A code like 4R7 means 4.7 pF. Very small capacitors may use direct numbers instead of multiplier codes. Larger multilayer parts may include rated voltage marks. Treat unknown letters as clues, not proof. Check a datasheet when safety, heat, or voltage is involved.

FAQs

What does capacitor code 104 mean?

Code 104 means 10 followed by four zeros in picofarads. The value is 100,000 pF, which equals 100 nF or 0.1 µF.

What does the letter K mean on a capacitor?

K usually means the capacitor tolerance is plus or minus 10 percent. The actual value may be 10 percent above or below the printed value.

Is a three digit code always in pF?

For standard ceramic capacitor markings, yes. The three digit EIA code is decoded in picofarads before conversion to nF, µF, or farads.

How do I read 4R7 on a ceramic capacitor?

The letter R acts as a decimal point. A marking of 4R7 means 4.7 pF. This is common on small capacitance parts.

What is the difference between X7R and C0G?

C0G or NP0 is very stable and preferred for precision work. X7R gives higher capacitance in small packages but changes more with voltage and temperature.

Can this calculator check a measured capacitor?

Yes. Enter the measured value and choose its unit. If a tolerance is known, the tool reports whether the measurement is inside the expected range.

Why is voltage rating included?

Voltage rating tells how much voltage the capacitor can safely handle. Operating with margin below that rating improves reliability and reduces failure risk.

Can I use this for electrolytic capacitors?

This page is designed for ceramic capacitor markings. Electrolytic capacitors often print direct values, voltage, polarity, and series data differently.