need help how to select ac motor starter capacitor value

hi friend i have a small blower motor and how to choose a ac capacitor value to start ..and wat is the use of that capacitor ..is there any formula to calculate

input 230V ac

frequency 50HZ

Ohms--240

thanks

The cap value depends a lot on the motor parameters, your best bet is to see if you can find a similar motor and look at its capacitor.
Is the motor permanent capacitor or switched?