Capacitor Code Calculator
Enter a capacitor code or select values to decode the capacitance, voltage rating and tolerance. Supports 3-digit codes, surface-mount markings and direct value entry.
Reviewed by the ToolNestr Editorial Team — July 2026
Capacitor types by capacitance range
Different capacitor technologies are suited to different capacitance ranges. The chart below shows typical ranges for common capacitor types.
Electronics Repair Tech
Quickly identify unmarked capacitors on circuit boards during repairs and find suitable replacements.
Circuit Designer
Convert between code formats and capacitance units when selecting capacitors for new designs and BOM creation.
Electronics Hobbyist
Decode the mysterious numbers on ceramic capacitors and learn to pick the right component for your projects.
Electronics Student
Learn the capacitor numbering system and practice converting between pF, nF and \u00b5F units used in textbooks.
| 3-digit code | Calculated value | In nF | In \u00b5F | Common use |
|---|---|---|---|---|
| 101 | 100 pF | 0.1 nF | 0.0001 \u00b5F | RF decoupling |
| 102 | 1000 pF | 1 nF | 0.001 \u00b5F | Timing circuits |
| 103 | 10,000 pF | 10 nF | 0.01 \u00b5F | Filtering, bypass |
| 104 | 100,000 pF | 100 nF | 0.1 \u00b5F | Power supply decoupling |
| 105 | 1,000,000 pF | 1000 nF | 1 \u00b5F | Output filtering |
| 106 | 10,000,000 pF | 10,000 nF | 10 \u00b5F | Bulk storage |
How to use the Capacitor Code Calculator
Choose your mode
Select \u201cCode \u2192 Value\u201d to decode a capacitor marking, or \u201cValue \u2192 Code\u201d to find the code for a known capacitance.
Enter the code or value
Type the 3-digit code (e.g., 104) or enter a capacitance value with the correct unit (pF, nF or \u00b5F).
Read all conversions
The result boxes instantly display the value in pF, nF and \u00b5F simultaneously so you can compare across units.
Tips for reading capacitor codes
Always verify with a multimeter
Capacitors can drift from their marked value over time, especially electrolytics. Use a multimeter with capacitance measurement to verify the actual value when precision matters.
Watch for non-standard codes
Some manufacturers use codes like R47 (0.47 \u00b5F) where the letter indicates the decimal point. A code of \u201c4n7\u201d means 4.7 nF. These are common on film capacitors and SMD types.
Check the voltage rating
A ceramic 104 capacitor rated for 50V is much larger than one rated for 16V. Always check the voltage rating, which may be printed separately or encoded in the marking.
Understand tolerance codes
Tolerance is often marked with a letter: F=\u00b11%, G=\u00b12%, J=\u00b15%, K=\u00b110%, M=\u00b120%, Z=+80/-20%. For decoupling circuits, K or M is fine; for timing and filters, J or better is needed.
How capacitor codes work
The 3-digit capacitor code is the most common marking system for ceramic capacitors. The first two digits are the significant figures, and the third digit is the multiplier as a power of 10. The result is always in picofarads (pF). For example, code 472 means 47 \u00d7 10\u00b2 = 4700 pF = 4.7 nF. If the third digit is 8, multiply by 0.01; if it is 9, multiply by 0.1. Values below 10 pF often use a different system like R47 for 0.47 pF.
Electrolytic capacitor markings
Electrolytic capacitors print the value directly in microfarads (\u00b5F) along with the voltage rating, such as \u201c100 \u00b5F 25V\u201d. They also show polarity \u2014 a stripe on the side indicates the negative terminal (for aluminum electrolytics) or positive (for tantalum). The operating temperature range is often printed as well, typically -40\u00b0C to +105\u00b0C for standard types.
Tolerance and temperature coefficients
Ceramic capacitors are classified by temperature stability. Class 1 (C0G/NP0) has very stable capacitance with temperature, ideal for timing and RF circuits. Class 2 (X7R, X5R, Y5V) have higher capacitance density but vary with temperature and voltage. X7R varies \u00b115% from -55\u00b0C to +125\u00b0C, while Y5V can vary +22/-82% over its range.
Surface-mount capacitor identification
SMD capacitors in larger packages (1812 and above) may use a 3-digit code similar to through-hole types. Smaller packages (0402, 0603) are usually unmarked. Some use a two-character alphanumeric code where the letter represents the significant digits and the number is the multiplier. Without a code, the only way to determine the value is by measuring or referencing the schematic.
Worked example
Frequently asked questions
How do I read a 3-digit capacitor code?
The first two digits are the significant figures, and the third digit is the multiplier (number of zeros). For example, 104 means 10 × 10⁴ = 100,000 pF = 100 nF = 0.1 µF. The result is always in picofarads (pF).
What does a capacitor code like 221 mean?
221 decodes as 22 × 10¹ = 220 pF. If the code is 222, it is 22 × 10² = 2200 pF = 2.2 nF. The third digit is the power of ten multiplier applied to the first two digits.
How do electrolytic capacitors show their value?
Electrolytic capacitors typically print the value directly in microfarads (µF) along with the voltage rating, e.g., “100 µF 25V”. They may also show polarity with a stripe indicating the negative terminal.
What is the EIA capacitor marking system?
The EIA-198 standard uses a 3-digit code for capacitance and sometimes a letter for tolerance. The first two digits are significant, the third is the multiplier. A letter suffix like J, K, or M indicates tolerance (±5%, ±10%, ±20%).
What do the letters on capacitors mean?
Common letter codes: J = ±5%, K = ±10%, M = ±20%, Z = +80/-20%. Voltage codes: 1A = 10V, 1C = 16V, 1E = 25V, 1H = 50V. Some manufacturers use their own proprietary marking systems.
How do I convert between pF, nF and µF?
1 µF = 1000 nF = 1,000,000 pF. To convert: pF ÷ 1000 = nF, nF ÷ 1000 = µF, pF ÷ 1,000,000 = µF. A capacitor marked 104 is 100,000 pF = 100 nF = 0.1 µF.
What surface-mount capacitor markings should I look for?
Small SMD capacitors are often not marked due to size constraints. Larger sizes (1812 and above) may use a 3-digit code. Some use a two-character code with a letter for the significant value and a number for the multiplier.
Why do some capacitors have no visible markings?
Very small capacitors, especially SMD types in 0402 and 0603 packages, are too small to print legible codes. Their value must be determined from packaging, multimeter measurement, or the circuit schematic.
What is the voltage rating on a capacitor?
The voltage rating is the maximum DC voltage the capacitor can withstand continuously. Exceeding this rating can cause dielectric breakdown and catastrophic failure. Always use a capacitor rated at least 50% above the circuit’s operating voltage.
How do I decode a capacitor marked with a letter and number?
Some capacitors use a compact code like “A2” where the letter represents the base value (A=1, B=1.1, C=1.2, etc.) and the number is the multiplier power of 10. The final value is in pF. Reference charts are available for these codes.
Sources & references
This tool uses standard formulas and reference values from:
- • NFPA 70 — National Electrical Code (NEC), conduit fill, box fill and conductor ampacity. nfpa.org
- • IPC-2221, Generic Standard on Printed Board Design (trace width / current). ipc.org
- • NIST reference constants and unit definitions; IEEE standards where applicable. nist.gov
For educational and preliminary use. Verify against full engineering calculations and the governing standard before any real design.