Capacitor Code Calculator

Capacitor Code Calculator: Component Identification and Code Interpretation

Enter a supported numeric or R-coded marking to decode its nominal capacitance, or enter a value and unit to generate a numeric reference code. An optional trailing letter can provide tolerance context when it is one of the codes supported by the tool.

SMD and electrolytic capacitor code input notes

Use the calculator for printed value codes such as 104, 104K, 223, 475, 4R7, or 226M. SMD package codes such as 0603, 0805, and 1206 identify size, not capacitance, so they must be paired with the actual printed value, measurement, schematic, or datasheet. Electrolytic capacitors usually print direct uF, voltage, and polarity markings, such as 47 uF 25 V with a negative stripe, rather than a three-digit ceramic-style value code.

Step-by-step usage

1. Choose Decode code to value, Convert value to code, or Tolerance and rating analysis depending on the task.
2. Set the Capacitor Type to match the part family so you can review the correct tolerance and dielectric context.
3. For decode, enter a common marking such as 104, 223, 475, 104K, or 4R7. For encode, enter the capacitance value and unit (pF, nF, µF, mF).
4. When needed, add tolerance letter, voltage rating, and temperature coefficient so the calculator can report additional specification context.
5. Review the returned capacitance in pF and scaled units together with any tolerance or temperature-coefficient notes, then confirm manufacturer-specific ratings from the datasheet.

Supported calculator modes

• Decode code to value: Enter a 2–4 digit code such as 104, 223, 475, or 4R7. The tool returns capacitance in pF plus scaled units (nF/µF) and shows the 10^multiplier used.
• Convert value to code: Enter a capacitance value and unit (pF, nF, µF, mF). The tool generates a numeric reference code; confirm the applicable marking convention before using it to identify a part.
• Reference sections on this page: Use the SMD case-size table only to distinguish package dimensions from electrical markings. The calculator does not take package-size or color-band inputs.
• Tolerance and rating analysis: Use the available tolerance and temperature-coefficient lookups as label references. A voltage entered here is shown as context only; the tool does not evaluate performance over temperature or applied voltage.

Limits: The tool does not decode color bands, SMD package numbers, manufacturer-specific markings, or voltage-rating codes. Its tolerance and temperature-coefficient results are reference lookups; it does not calculate effective capacitance under DC bias, voltage derating, ripple limits, ESR, or replacement compatibility. Check the exact part number and operating conditions against its datasheet.

3-Digit Capacitor Code Reference After Using the Calculator

Use the calculator above for the actual marking on the component. This reference section explains the decoding rule after you enter the code; it does not replace the interactive decode result or the manufacturer datasheet.

• Three-digit numeric markings use the first two digits as significant figures and the third digit as the pF multiplier.
• R-coded markings use the letter R as a decimal point for small pF values.
• Tolerance suffixes such as J, K, or M should be entered with the marking so the calculator can keep capacitance and tolerance context together.
• Package numbers such as 0603, 0805, and 1206 identify physical size, so confirm the electrical value from the printed marking, schematic, measurement, or datasheet.

Key rule: decode the printed marking first, then convert the returned pF value into nF or uF only after the calculator has identified the numeric pattern and any tolerance suffix.

Common Capacitor Code Lookup Reference After Decoding

For common markings such as 104, 223, 475, 4R7, or 226M, enter the printed code in the calculator and use the returned pF, nF, and uF values before selecting a replacement. Keep the decoded value, tolerance suffix, capacitor family, and datasheet context together when you compare the result with a chart or parts list.

When you need a quick reference sheet instead of a one-off decode, use the Capacitor Code Chart, then move to the RC Circuit Calculator for timing networks or the Capacitor Calculator for reactance checks.

Understanding Capacitor Coding Systems and Standards

Capacitor code identification requires understanding multiple marking systems used by different manufacturers and capacitor technologies. Ceramic capacitors typically use 3-digit numeric codes, while tantalum and electrolytic capacitors may use direct value markings or alphanumeric codes. Surface-mount devices (SMD) use compact coding systems due to space constraints.

Marking conventions vary by component family and manufacturer. This calculator covers only the numeric and R-coded formats described above; a matching decoded capacitance does not establish that a replacement has the required voltage rating, dielectric, polarity, package, or circuit performance. Verify standards-specific marking interpretations against the applicable standard or manufacturer documentation.

Capacitor families and marking limits

Markings the calculator does not decode

Color bands, package-size codes, direct-value markings, and manufacturer-specific series codes are outside the calculator inputs. Use the original equipment documentation or the exact part datasheet to identify those markings; the SMD size table below is only a dimension cross-reference.

EIA 198 Standard SMD Capacitor Size Codes

The table is a dimensional cross-reference between common imperial and metric SMD case designations. The case code does not identify capacitance, dielectric, or voltage rating. Confirm the exact package dimensions and electrical limits in the part datasheet; standards-specific designation details require verification against the applicable standard.

Voltage Ratings and Derating Practice

Voltage may appear as a printed value or as part of a manufacturer-specific part number. This tool does not decode voltage markings; use the exact part datasheet for its permitted DC and AC conditions.

This calculator displays a voltage value entered by the user; it does not determine an acceptable operating voltage or derating margin. Compare the circuit waveform and operating conditions with the exact part datasheet and its manufacturer guidance.

For a system-level USB Power Delivery decoupling workflow, see the USB Power Delivery decoupling and capacitor selection guide. This code tool does not determine rail voltage, select capacitors, or calculate voltage margin.

The separate design guide covers checks such as:

• Determine the maximum negotiated bus voltage and expected transient overshoot on the USB‑PD rail.
• Select a combination of local MLCCs (for high-frequency decoupling) and bulk capacitors (for lower-frequency energy storage) consistent with the controller or converter reference design.
• Use the selected part's datasheet and converter reference design to determine voltage margin and effective capacitance; this calculator does not perform that selection.
• Check effective capacitance under DC bias at the actual bus voltage using datasheet graphs or vendor tools, and verify the resulting impedance profile against your PD controller or power-stage specifications.

Advanced Capacitor Code Interpretation and Specifications

Temperature-coefficient lookup: The calculator reports reference text for the supported labels C0G, X7R, Y5V, Z5U, X5R, and X8R. It does not model a specific part's capacitance over temperature, DC bias, or applied voltage; use the selected manufacturer's datasheet for those conditions. For a separate coefficient lookup, use the Temperature Coefficient Calculator.

Voltage rating: The calculator can retain a user-entered voltage as context, but it does not decode manufacturer voltage codes or calculate a safe rating. Confirm the marking and permitted operating conditions in the datasheet.

Tolerance: The lookup reports only the tolerance codes available in the calculator. It does not calculate circuit error or determine whether a tolerance is suitable for a design.

Practical Capacitor Identification and Replacement Guidelines

Package-size codes identify dimensions, not capacitance or electrical ratings. For a separate reactance calculation, use the Capacitor Calculator; for an RC time-constant calculation, use the RC Circuit Calculator.

Component identification and replacement

A decoded capacitance is not enough to confirm a replacement. Verify the full part number, dielectric, voltage rating, polarity, package, tolerance, temperature behavior, and circuit requirements using the equipment documentation and manufacturer datasheet. Use the RC Circuit Calculator for a separate time-constant calculation or the Capacitor Calculator for a capacitance/reactance calculation; neither lookup replaces part-specific specifications.