| Printed capacitance | A value in farads, microfarads (µF), nanofarads (nF), or picofarads (pF), such as 100 µF. | The component’s nominal capacitance. | Confirm the unit carefully. A marking of 100 nF equals 0.1 µF. |
| Three-digit code | A code such as 104 or 472. | On many ceramic capacitors, the first two digits are significant figures and the third is the number of zeros in pF. For example, 104 is 100,000 pF (100 nF); 472 is 4,700 pF (4.7 nF). | This convention is common, not universal. Check the component’s datasheet or a reliable code reference, especially for short or unusual markings. |
| Rated voltage | A voltage value, often printed with a unit such as 25 V or 250 V. | The maximum specified operating voltage under stated conditions. | Do not exceed the rated voltage. A higher voltage rating does not by itself identify the dielectric or capacitor family. |
| Polarity marking | A plus sign, a marked positive lead, or a stripe that identifies a terminal. | May indicate a polarized electrolytic capacitor and help distinguish its terminals. | Stripe conventions vary by capacitor type and manufacturer. Some electrolytic capacitors are bipolar; verify the specific part marking before installation. |
| Physical construction | Disc or multilayer ceramic, wound film, metal can, or another visible form; note lead style and dimensions. | Provides clues to the capacitor family and likely application. | Appearance alone is not conclusive: different dielectric types and ratings can share similar shapes. |
| Dielectric or series code | Letters or alphanumeric markings, such as a dielectric code, series identifier, or temperature-characteristic code. | May specify dielectric material, tolerance, temperature behavior, or a product series. | Codes depend on the relevant standard and manufacturer. Use the exact marking with a datasheet or catalog rather than guessing. |
| Tolerance and temperature rating | A percentage, letter code, temperature range, or temperature-characteristic marking. | Describes how much capacitance may vary and how performance changes with temperature. | Interpret letter codes in context; the same letter can mean different things under different marking systems. |
| Electrical measurement | Capacitance measured with a suitable meter, compared with the printed value and tolerance. | Can help check whether an unmarked or questionable component is electrically plausible. | Remove the capacitor from the circuit where practical. Discharge it safely first; in-circuit readings may be affected by other components. |
| Exact identification | All markings, dimensions, lead spacing, and package details matched to a datasheet. | Confirms the specified capacitance, voltage, dielectric, tolerance, temperature range, and other ratings. | When markings are incomplete or ambiguous, do not infer a precise part type from appearance alone. Obtain the original documentation or replace it with a verified equivalent. |