Why loan comparisons need the same ending date
A lower payment can leave a larger liability at the end of your comparison.
Count both cash and debt
At the chosen future month, add cash already paid to the outstanding payoff amount. Do the same for every alternative. Upfront closing costs and principal reductions belong in cash paid. Financed costs belong in the new principal; counting them again as cash doubles the charge.
Different terms need special care
A new thirty-year loan can have a smaller payment than an existing loan with twenty years left. That does not automatically produce a lower cost. At a five-year comparison date, the new loan can leave substantially more principal.
Discounting is a valuation assumption
The points calculator optionally discounts future payments and terminal debt to today. Zero discount compares nominal amounts. A positive rate is supplied by you and does not mean the difference could certainly earn that return elsewhere.
What is outside the model
Taxes, insurance, cash-out proceeds and investment returns on cash savings are excluded unless a tool explicitly includes them. Results are comparisons of the stated scenarios, not mortgage recommendations.