Capacitor Size

Discussion in 'General Electronics Chat' started by Prabu1004, Apr 17, 2013.

  1. Prabu1004

    Thread Starter New Member

    Apr 17, 2013
    One doubt on the Capacitor Size.
    By theory, larger the value of capacitor can be obtained if the distance of separation between the two plates are smaller. C = εA/d
    But in general, larger value capacitors are bigger and larger in size. Why ?
  2. crutschow


    Mar 14, 2008
    Because to get more capacitance requires more plate area (A), given that the distance between plates (d) is reduced as much as practical for a given dielectric. Since electrolytics use a very thin chemical dielectric to give the minimum practical distance between plates, they have the largest capacitance of any capacitor type for a given physical size.
    Prabu1004 likes this.
  3. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    One interesting rule of thumb that follows for this is the size of a cap can be estimated from one cap of that series. As crutschow correctly states the plate size for a given capacitance follows from the dielectric, since a minimum spacing must be maintained for a given voltage.

    The rule of thumb is for a given series voltage x capacitance is proportional to the physical size.

    So say you have a 10 uF 10V cap, but need a larger voltage. A 10 uF 20V cap would be larger, but if you could get something close to a 5uF 20V cap it should come in the same case size.
  4. #12


    Nov 30, 2010
    Saying the same thing in a different way, the manufacturers always use the closest spacing they can for a given voltage rating, then add more area to get larger amounts of capacitance.

    Great advancements have been made in thin film (insulator) technology in the last 20 years. Capacitors are a LOT smaller than they were 20 or 40 years ago, but 100 uf still requires 10 times as much total area as a 10 uf capacitor.