# How to determine total tolerance of a ceramic capacitor?

For the sake of this question (as an example only) lets consider MLCC X7R ceramic capacitor. Such a component among others is characterized by a number of tolerances. Temperature dependeant tolerance, DC bias voltage tolerance or aging tolerance as a few of them might be listed. Ommitting the problem of determining tolerances themselves (assuming knowledge of particular tolerances values), how to calculate total tolerance of a capacitor?

Is it just a sum of all tolerances or it is more complicated (e.g. there exists some sort of tolerance "propagation")?

• I suspect the characteristic tolerances are not just summed up because those variables all fall into some physics equation somewhere, and the individual error of variables in an equation are not just summed together. When you calculate the total error of such an equation, you have to handle each variable differently depending on where it appears in the equation ( with an addition, multiplication, division, square root, exponent, etc). There are general rules you can look up but you would need that capacitor equation. Error Propagation: lectureonline.cl.msu.edu/~mmp/labs/error/e2.htm – DKNguyen Apr 25 '19 at 22:19
• @Obcy - this can get a little tricky... if it's something deterministic, like capacitance change over DC bias, for instance, then simply adding is the way to go. If it's something intrinsically random, like part-to-part capacitance variation, then it makes more sense to add the squares of the standard deviations to get the total standard deviation squared. – joribama Apr 26 '19 at 0:47
• Depends on WHO SUFFERS that 0.003% of the time when all the tolerances stack up? Is this a TOY that ceases working at cold temperatures and old-discharged battery? Or is this a bit-clock-tracking phase-lock-loop, and the loop filter cap changes and the JITTER soars and the PACKET BIT ERRORS increase from 1 part per Trillion to 1part per 100/ – analogsystemsrf Apr 26 '19 at 4:40