Loan Overpayment Calculator

Extra payments and lump sums go entirely toward principal, since the scheduled payment already covers that period's interest — this shrinks the balance interest accrues on for every remaining period of the loan, which compounds into meaningful savings the earlier it happens.

A recurring extra payment adds a fixed amount to every regular payment going forward. A lump sum is a single one-time payment (like a bonus, tax refund, or inheritance) applied once to immediately reduce the balance — this calculator lets you model either, or both together.

Yes — the math is the same fixed-rate amortization used for mortgages, auto loans, personal loans, and most other installment loans. It doesn't apply to loans with prepayment penalties, which some lenders charge for paying off early — check your loan agreement first.

Check your loan for a prepayment penalty clause first. Also consider whether that money would be better used building an emergency fund, paying off higher-interest debt elsewhere, or investing — overpaying a low-rate loan isn't always the best use of extra cash.