# 1st Order Passive Filter Calculator

RC LPF Calculator
Calculate Frequency(fc):

Results:

φ= 45° and Xc=R at cutoff frequency fc

Calculate R(=Xc):

Results:

Calculate C:

Results:

Calculate φ:

Results:

Calculate E & τ:
V

Results:
Energy stored in C
Time Constants:
63.2% of its final value
within 0.01% of its final value

Formula:
Cutoff frequency:
$$f_0=\frac{1}{2 \pi R C}$$
Capactive Reactance:
$$X_C=\frac{1}{2 \pi f_0 C}$$
RL LPF Calculator
Calculate Frequency(fc):

Results:

Calculate R(=XL):

Results:

Calculate L:

Results:

Formula:
Cutoff frequency:
$$f_0=\frac{R}{2 \pi L}$$
Inductive Reactance:
$$X_L=2 \pi f_0 L$$
RC HPF Calculator
Calculate Frequency(fc):

Results:

Calculate R(=XC):

Results:
Calculate C:

Results:

Formula:
Cutoff frequency:
$$f_0=\frac{1}{2 \pi R C}$$
Capactive Reactance:
$$X_C=\frac{1}{2 \pi f_0 C}$$
RL HPF Calculator
Calculate Frequency(fc):

Results:

Calculate R(=XL):

Results:

Calculate L:

Results:

Formula:
Cutoff frequency:
$$f_0=\frac{R}{2 \pi L}$$
Inductive Reactance:
$$X_L=2 \pi f_0 L$$