By Michael Logan, Updated March 24, 2022
Capacitors act as temporary energy storage devices, holding electrical charge without generating it. The amount of charge a capacitor can store is quantified in farads, but most components are rated in microfarads or picofarads. K5M capacitors—constructed from ceramic, mylar, or mica—span values from a single picofarad up to 0.47 µF.
Identify the first two digits of the numeric code; these are the significant figures. For example, a marking of 224M means the significant figures are 22.
Append zeros according to the third digit. In the example above, the third digit is 4, so add four zeros to 22 to obtain 220,000 picofarads (0.22 µF).
Consult the letter code to determine tolerance. The letter following the numeric code indicates the permissible variation. For instance, the suffix M corresponds to ±20 %, yielding a range of 176,000 to 264,000 picofarads for a 220,000‑pF capacitor.
Look for a secondary letter code (usually two letters beneath the first line). This code identifies the dielectric material separating the capacitor’s plates.
Capacitors below 100 pF are typically stamped directly with the capacitance value, e.g., a 22‑pF capacitor will read "22pF" followed by its tolerance code. Color bands may also indicate temperature coefficient.
