How does load resistance affect RC low pass filter?
You can use the Thevenin equivalent circuit to see what your capacitor &quot;sees&quot;.
Your capacitor will see an input voltage of Vin*R2/(R1+R2) in series with a resistor equal to (R1||R2). Hence your load will affect your voltage amplitude and also your cut-off frequency. If it is a problem, you may use an op-amp configured as a voltage follower between the output of your filter and your load.