with filter calculator pro you can calculate the parameters or components of a passive RL, RC, LC, Butterworth, Bessel, Chebyshev, and active filter.

Filter calculator has the following features:
RC filter calculations
RL filter calculations
LC filter calculations
Passive Butterworth filter calculations (2,3,4, and 5 pole Butterworth filter)
Active Butterworth, Bessel, Chebychev filter calculations
Notch filter
Passive cross over design
Band pass filter

filter design is suitable for the design of electronic filter and electronics troubleshooting as well as students of electronics engineering
You can choose to calculate the parameters of the filter or calculate the circuit components.