Capacitor Code Calculator
Free online capacitor code calculator. 100% client-side.
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What is Capacitor Code Calculator?
The Capacitor Code Calculator decodes the numeric markings printed on ceramic capacitors. Small capacitors are too tiny for full value printing, so manufacturers mark them with a 2–3 digit EIA code: the first two digits are significant figures and the third is the number of zeros, all in picofarads — 104 means 10 × 10⁴ pF = 100 nF = 0.1 µF. Values below 10 pF use R as a decimal point (4R7 = 4.7 pF), and a trailing letter such as J, K, or M adds the tolerance. The tool also works in reverse, converting any capacitance back into the code printed on the part. All math runs locally in your browser.
Key Benefits
- Decode cryptic 3-digit markings instantly without a printed chart
- Bidirectional: also find the code to look for from a target value
- R decimal notation and the full EIA-198 tolerance letter table built in
- Quick-reference grid of the 18 most common ceramic codes
- 100% client-side and offline-capable — nothing is uploaded
Common Use Cases
- •Identifying unmarked parts in a salvage or parts bin
- •Checking homework and reading EIA codes in electronics class
- •Ordering replacements: find the marking code for a value you need
- •Decoding SMD ceramic caps on production or repair benches
- •Converting between pF, nF, and µF while reading datasheets
How to Use the Capacitor Code Calculator
- Pick a mode: Choose Code → Value to decode a marking, or Value → Code to find the marking for a capacitance.
- Enter the code or value: Type the marking as printed on the part (e.g. 104, 4R7, 223K) or enter a capacitance with its unit (pF, nF, µF).
- Read the result: The decoded value appears in pF, nF, and µF with the sig × 10^multiplier math shown, plus the tolerance if a letter is present.
- Copy or explore: Copy the result summary, or tap any code in the quick-reference grid to decode it instantly.
Key Features
- Decode 2/3-digit EIA codes and R decimal notation to pF, nF, and µF instantly
- Encode mode: turn any capacitance back into the marking code to look for
- Tolerance letter parsing with the full EIA-198 / IEC 60062 table
- Clickable reference grid of the 18 most common ceramic capacitor codes
- Copyable summary with the sig × 10^multiplier math shown
- 100% client-side — works offline, nothing is uploaded
Frequently Asked Questions
What does the capacitor code 104 mean?
The first two digits are significant figures and the third is the multiplier (number of zeros) in picofarads: 10 × 10⁴ pF = 100,000 pF = 100 nF = 0.1 µF.
How do I read codes like 4R7 or 0R5?
The letter R marks the decimal point in pF, used for values below 10 pF: 4R7 = 4.7 pF and 0R5 = 0.5 pF.
What do the letters J, K, and M after the code mean?
They are tolerance codes from EIA-198 / IEC 60062: J = ±5%, K = ±10%, and M = ±20%. So 104K is 100 nF with ±10% tolerance.
Why are capacitors marked in pF instead of µF?
The EIA code system was designed around picofarads to keep every ceramic part on one consistent scale — from single-digit pF parts up to 10 µF (106) — using only 2–3 digits.