I found out that this ‘calculation’ was wrong. I paid a lump sum at the beginning which invalidates this savings I stated. I’m actually farther along than I thought, but as a result the time frame for the $50 to have an effect is diminished, so the savings directly from the $50 at this point is less than what I thought.

Yeah, the website I used just asked for the 1) principal amount, the 2) interest rate, the 3) remaining term, and 4) amount of extra paid each month. I realized that the exact amount I’ve saved is probably more than that. With my first payment I paid a lump sum extra on the principal, and my term is not recalculated automatically on my monthly bill.