Vehicle EconomicsExtra Car Payment Savings
An extra payment goes straight to principal, and principal paid off early stops accruing interest for every month that follows. Enter your loan to see the real payoff.
Sensitivity: extra monthly payment
Drag to see the payoff and savings change live, without touching the form above.
Why this comes up
Rounding a payment up, or throwing an extra $50-100 at the loan each month, is one of the easiest ways to cut interest cost, but it's hard to know how much it actually matters without running real numbers. This engine turns a habit into a concrete figure: months and dollars saved.
How we calculated this
We run the loan's amortization schedule twice, once at the stated payment alone, once with the extra applied every month, and compare payoff month and total interest.
Worked example, using this page's own defaults ($15,000 balance, 6% APR, 48 months remaining, $100/month extra): the loan pays off noticeably earlier and saves real interest versus the baseline. Run the calculator above for the exact numbers.
What this means
- Savings scale faster than the extra dollar amount, because less balance accrues interest for less time, doubling the extra payment usually more than doubles the interest saved.
- If you're deciding whether to prepay or invest that cash instead, compare this guaranteed savings rate against what the cash could otherwise earn.
- For a one-time lump sum instead of a recurring extra, see Auto Loan Early Payoff Calculator, which handles both together.
Limitations
Assumes the extra payment applies directly to principal every month with no lender-side prepayment penalty or restriction. See Methodology.
Methodology
This engine is built on Vehicle Economics' fixed-rate amortization model: the standard loan-payment formula run out as a full month-by-month schedule. See Methodology for the full detail.