Capacitance Conversion — pF · nF · μF · mF · F

The story of capacitance begins in October 1745 in Pomerania, where Ewald Georg von Kleist charged a glass jar filled with water and wire and received a shock that nearly killed him. Pieter van Musschenbroek replicated the experiment at Leiden University in 1746, and the device became known as the Leyden jar — the world's first capacitor. Alessandro Volta coined the word "condensatore" for these devices in 1782, a term still used in German (Kondensator), French (condensateur) and Italian.

Michael Faraday, working alone at the Royal Institution between 1831 and 1838, formalized the modern concept of capacitance. His 1838 Bakerian Lecture "On Static Electrical Inductive Action" introduced the dielectric constant — what he called "specific inductive capacity." The unit "farad" was proposed in his honor at the First International Electrical Congress in Paris in 1881 by Sir William Thomson (Lord Kelvin). The CGPM (General Conference on Weights and Measures) formally adopted it as the SI coherent unit in 1948, defining 1 F = 1 C/V.

The SI prefix system that the decade turret implements was codified in stages by the CGPM and overseen by the BIPM (Bureau International des Poids et Mesures) in Sèvres, France. The kilo-, milli- and micro- prefixes existed informally from the 1795 metric system. Nano- and pico- were formalized at the 11th CGPM in 1960. The 26th CGPM in 2018 redefined the kilogram, ampere, kelvin and mole via fundamental constants, indirectly pinning the farad to the Planck constant and elementary charge — making the dial markings on this turret traceable to natural law rather than physical artifacts.

Practical capacitor manufacturing scaled with the decade prefixes through the 20th century. The first commercial paper-foil capacitors of the 1910s lived in the nF range. Aluminum electrolytics, invented by Charles Pollak in 1896 and commercialized by Cornell-Dubilier in the 1930s, opened the μF decade. The 1950s brought ceramic dielectrics into the pF-nF range and tantalum into the 10-100 μF range. The 2000s introduced double-layer supercapacitors that finally populated the F decade — closing the loop on Faraday's original unit, which for 130 years had been impractically large for any single device.

The IEC 60384-1 standard (latest revision 2016) governs fixed capacitor marking and testing worldwide. The companion EIA-198 in the United States and JIS C 5101 in Japan harmonize with it. The 3-digit code on every SMD ceramic — "104", "221", "472" — is read in picofarads with the third digit as the exponent. The decade turret is therefore not just a converter but a marking decoder: type 100,000 into the pF dial and you see the "104" capacitor as 100 nF and 0.1 μF simultaneously.

Modern supercapacitor research, led by Patrice Simon at CNRS-Toulouse and Yury Gogotsi at Drexel University, is pushing single-cell capacitance into the kF (kilofarad) range using MXene and graphene electrodes. The decade turret in this widget intentionally caps at 1 F because anything above is still rare commercial territory. But the prefix math extends without limit — kF, MF, GF capacitors are no different in principle, only in fabrication.