RC Low-Pass Filter Design

I need a clean, passive low-pass filter designed around standard resistor-capacitor (RC) components. The target cutoff is comfortably below 1 kHz, so I expect calculations that clearly show the ‑3 dB point in that region and justify the chosen values.

Please deliver:
• A schematic with labelled part values
• The formula walkthrough that leads to those values (including impedance considerations)
• A brief frequency-response plot or SPICE simulation screenshot confirming the roll-off

Keep the layout simple enough for through-hole assembly and aim for readily available E12 series parts. If you like working in LTspice, Multisim, or a similar tool, feel free—the files are welcome alongside a PDF or image of the final circuit.