Capacitor Code Decoder (Ceramic EIA & Film Markings)

Reading capacitor codes

Small ceramic and film capacitors are too small to print a full value, so they use the same 3-digit EIA code as SMD resistors, but the result is always in picofarads: the first two digits are significant figures, the third is a power-of-ten multiplier. 104 = 10 × 10⁴ pF = 100,000 pF = 100 nF = 0.1 µF. A trailing letter gives tolerance (J = ±5%, K = ±10%, M = ±20%; B/C/D are tight absolute tolerances used only on very small <10 pF caps). Two-digit codes with no multiplier (e.g. "10") are read directly as picofarads.

Larger film capacitors often skip the EIA code and print the value directly, using a letter as the decimal point and unit marker: p for pF, n for nF, u/µ for µF. So 4n7 = 4.7 nF and n47 = 0.47 nF. A plain number with no letter and a leading dot (.1, .22) is conventionally read in µF.

When in doubt, check against context: coupling/decoupling caps near ICs are usually 10 nF–100 nF (ceramic), bulk filtering is µF-range (often electrolytic, value printed directly), and RF-tuning caps are single- or double-digit pF.