Capacitor Code Decoder

How do 3-digit capacitor codes work?

The 3-digit capacitor code system (EIA-198) is used to mark ceramic, film, and other small capacitors where the body is too small for a full value print. The code expresses capacitance in picofarads: the first two digits are significant figures, and the third digit is the power-of-10 multiplier.

For example, code '104' means 10 × 10⁴ = 100,000 pF = 100 nF = 0.1 μF. Code '472' means 47 × 10² = 4,700 pF = 4.7 nF. Codes ending in '0' have no multiplier (×1), while codes with '8' or '9' as the third digit use multipliers 10⁻² and 10⁻¹ respectively, yielding sub-picofarad values.

This system is analogous to resistor marking codes. Some capacitors also include a letter suffix indicating tolerance (J = ±5%, K = ±10%, M = ±20%) and a voltage rating code. Understanding these codes is essential for identifying unmarked components during repair or inventory management.

Formula: C(pF) = (D1 × 10 + D2) × 10^D3 where D1, D2 = significant digits D3 = multiplier exponent Special: D3=8 → ×0.01, D3=9 → ×0.1

Example Calculation

Code '473': D1=4, D2=7, D3=3. Capacitance = 47 × 10³ = 47,000 pF = 47 nF = 0.047 μF. This is a common value used for decoupling and filtering in digital circuits.

When to Use This Calculator

• Identifying unmarked or poorly labeled ceramic capacitors during PCB repair, rework, or component salvage
• Verifying the correct component was placed during manual assembly by decoding the printed code against the BOM
• Converting between picofarad, nanofarad, and microfarad representations when different data sheets use different units
• Teaching or learning electronics — quickly checking the decoded value reinforces understanding of the marking system

Common Mistakes to Avoid

• Forgetting that the base unit is picofarads — code '104' means 10 × 10⁴ pF = 100,000 pF = 100 nF = 0.1 μF, not 104 pF
• Misinterpreting codes with third digit 0 — '100' means 10 × 10⁰ = 10 pF, '200' means 20 pF, '470' means 47 pF; these are small values, not hundreds of picofarads
• Confusing capacitor codes with resistor codes — the same 3-digit marking system is used for resistors but in ohms; context (component type and size) determines which system applies
• Ignoring voltage rating and tolerance markings — some capacitors include additional letters or numbers after the 3-digit code that indicate voltage class and tolerance

How to Interpret Results

• A 3-digit code is two significant figures followed by a power-of-ten multiplier in picofarads — "104" = 10 × 10⁴ pF = 100,000 pF = 100 nF = 0.1 µF.
• The pF / nF / µF columns are the same value in different units; pick the unit your schematic or BOM uses to avoid 1000× ordering errors.
• A trailing tolerance letter printed on the part is separate from the 3-digit code and is not decoded here — read it from the marking directly.
• Values below 100 pF are often printed as the plain number (e.g., "47" = 47 pF), so a two-digit marking is not always a coded multiplier.

Related Standards & References

• EIA-198 — Ceramic dielectric capacitor marking codes, defining the 3-digit code system
• IEC 60062 — Marking codes for resistors and capacitors, including tolerance letter designations (J, K, M)

Frequently Asked Questions

What do the third-digit values 8 and 9 mean in capacitor codes?

Unlike digits 0–7 which represent multipliers of 10⁰ to 10⁷, digit 8 means ×0.01 and digit 9 means ×0.1. For example, code '158' = 15 × 0.01 = 0.15 pF, and code '159' = 15 × 0.1 = 1.5 pF. These are used for very small capacitance values in RF and high-frequency circuits.

How can I tell a capacitor code from a resistor code on an unmarked SMD component?

SMD capacitors (MLCCs) are typically unmarked or use the 3-digit pF code system. SMD resistors use a 3 or 4-digit ohm code (e.g., '103' = 10 kΩ). Physically, SMD capacitors tend to be squarer with no markings, while resistors are rectangular with printed codes. When in doubt, measure with a multimeter's capacitance mode.

Are there capacitor codes that can be confused with common values?

Yes. Code '105' (1 μF) and '104' (100 nF) are the most commonly used codes and easy to read correctly. But code '100' (10 pF, not 100 pF) catches people off guard — the third digit '0' means ×1, not ×10. Similarly, '101' = 100 pF (10 × 10¹), not 101 pF. Always apply the formula: first two digits × 10^(third digit) in picofarads.