Enter the two resistances R1 and R2 and the two capacitances C1 and C2 into the calculator to determine the cutoff frequency of the bandpass filter.

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## Bandpasss Filter Formula

The following formula is used to calculate the cutoff frequencies of a bandpass filter.

LCF = 1/2*pi*R2*C2

HCF = 1/2*pi*R1*C1

- Where LCF is the lower cutoff frequency (hz)
- HCG is the high cutoff frequency (hz)
- R1 and R2 are the resitances in a passive bandpass filter
- C1 and C2 are the capacitances in a passive bandpass filter

## Example Problem

**How to calculate the cutoff frequencies of a bandpass filter? **

First, deter the resistance and capacitance of C1 and R1. These should be as depicted below in the circuit.

For this example, the first capacitances and resistances are 10 farads and 4 ohms respectively. Keep in mind these may not be realistic for real-world bandpass filters but can be used to show the calculations more simply.

Next, determine the second capacitance and resistance. In this case, these values are found to the 5 farads and 2 ohms respectively.

Finally, calculate the lower and upper cutoff frequencies.

LCF = 1/2*pi*R2*C2

= 1/(2*3.14159*5*2)

= .0159 hz

HCF = 1/2*pi*R1*C1

= 1/(2*3.14159*10*4)

= .00397 hz.