Capacitor Value Code Reader
Decode capacitor value codes (3-digit and color band) to get the capacitance in pF, nF, and µF.
Also convert between units.
Capacitors are one of the most fundamental electronic components. They store electrical charge and are used in power supplies, filters, oscillators, timing circuits, and signal coupling. Reading their value from the markings on their body is an essential skill for anyone working with electronics.
The 3-Digit Capacitor Code
Most small ceramic and film capacitors use a 3-digit code stamped on their body. The code system works similarly to resistor color bands:
- First two digits: The significant figures of the capacitance value
- Third digit (multiplier): A power of ten (number of zeros to add)
- Result: The value in picofarads (pF)
Examples
| Code | First Two Digits | Multiplier | Value |
|---|---|---|---|
| 104 | 10 | × 10,000 (10⁴) | 100,000 pF = 100 nF = 0.1 µF |
| 472 | 47 | × 100 (10²) | 4,700 pF = 4.7 nF |
| 221 | 22 | × 10 (10¹) | 220 pF |
| 103 | 10 | × 1,000 (10³) | 10,000 pF = 10 nF = 0.01 µF |
| 100 | 10 | × 1 (10⁰) | 10 pF |
| 332 | 33 | × 100 | 3,300 pF = 3.3 nF |
Special Multiplier Codes
- Code 8 = × 0.01 (used for values under 10 pF)
- Code 9 = × 0.1
Tolerance Codes
A letter after the 3-digit code indicates tolerance:
- B = ±0.1 pF, C = ±0.25 pF, D = ±0.5 pF
- F = ±1%, G = ±2%, J = ±5%, K = ±10%, M = ±20%
Capacitance Unit Reference
1 µF (microfarad) = 1,000 nF = 1,000,000 pF
Common values:
- Ceramic bypass capacitors: 100 nF (0.1 µF) — code 104
- Electrolytic filter caps: 10–10,000 µF (marked directly in µF)
- Timing/signal coupling: 1 nF – 10 µF
- RF circuits: 10–100 pF
Voltage Rating
The voltage rating (e.g., 25V, 50V) must exceed the circuit voltage or the capacitor can fail. For electrolytics, polarity must also be observed — reversing polarity can cause violent failure.