Capacitor For Power Supply Calculator

This tool calculates the cap value (Farad) for a power supply. The power supply is either a full-wave or half-wave rectifier.



  • Type of power supply
  • Desired ripple voltage (ΔV),
  • Load current (I)
  • Frequency of the power supply (f)



Example Calculation

For a full-wave rectifier, with a load current of 2 Amp, 60 Hz frequency and Ripple Voltage of 1 Volt the required capacitor is 16.7 mF. For a half-wave rectifier with the same input parameters, a 33.3 mF cap is required.

Note the larger the value of the cap, the larger the RC time constant. This is consistent with the fact that with a half wave rectifier, the settling (or discharge) time is longer.


C = ILOAD/(2*f*VRipple) for a full wave rectifier

C = ILOAD/(f*VRipple) for a half wave rectifier


  • ILOAD is the load current
  • f is the frequency
  • VRipple is the peak-to-peak voltage ripple (calculator)

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