Loan Extra Payment Savings Calculator

The standard monthly payment is computed with the same fixed-rate amortization formula the Loan Payment Calculator uses: M = P·r(1+r)ⁿ / ((1+r)ⁿ − 1). This calculator then re-amortizes the loan month by month at that standard payment plus your extra amount — interest first on the remaining balance, then the rest toward principal — and tracks how many months it actually takes to reach zero.

Because interest is charged on a shrinking balance every month, a fixed extra payment compounds its own effect: each dollar of extra principal paid today is a dollar that never accrues interest again, which shrinks every future month's interest charge too. That's why even a modest extra payment tends to cut off a disproportionate share of the loan's total interest, not just its final few payments.

The chart below re-traces the accelerated schedule's cumulative principal-vs-interest split, stopping at the new (earlier) payoff month rather than the original term.