RC Filter Callculation

I am using a WCS 1700 Hall effect sensor to read current .

The Amps reading I am using currently is an average of 10 readings.Every time Current is calculated the A0 pin is read 100 times with a delay of 3ms.

I Read about using C or RC filters between A0 and Ground.

The Frequency for an RC is Fc=1/(2πRC)

I do understand that Fc is going to be the frequency above which nothing gets through but fail to understand quantitatively what is this number for my setup.

No your understanding is wrong about a filter. There is never a frequency where nothing gets through. The cut off frequency is where the output is half the input.

Think of the RC filter as a potential divider where the bottom leg is a frequency dependant resistor.

If you are sampling every 3ms, why not set RC = 3ms? the time-constant for an RC filter
is just RC.

But perhaps more importantly what bandwidth of signal do you want to obtain? You should always
sample at least twice (in practice more than 3 times) the signal bandwidth - and your anti-aliasing
filter should be matched to your sampling frequency.

So I guess the question is what are you measuring?