Extra Payment Savings Calculator
Think of your loan as a bucket that refills itself with interest every single month. Your regular payment barely keeps up with the refill early on — but every extra dollar you throw in skips the refill entirely and drains the bucket directly. See exactly how many years and how much interest that saves you.
Why extra payments save more than they seem to
Every regular loan payment you make is split into two pieces: a chunk that covers the interest for that month, and whatever’s left over goes toward your actual balance (the principal). Early in a loan — especially a mortgage — most of your payment is eaten by interest, and only a small sliver chips away at what you actually owe. An extra payment skips that split entirely: 100% of it goes straight to principal. That smaller principal means next month’s interest charge is calculated on a smaller number too — which is why the savings snowball instead of adding up in a straight line.
E = your regular monthly payment · P = loan amount · r = monthly interest rate (annual rate ÷ 12)n = total number of monthly payments over the loan term
Where should extra payments actually go?
- Check for prepayment penalties first. Some loans (less common today, but still worth checking) charge a fee for paying early. A quick look at your loan agreement or a call to your lender settles this in minutes.
- Confirm the extra amount is applied to principal, not “next month’s payment.” Some lenders default to holding extra payments toward your next due date instead of reducing principal immediately — you may need to specify this explicitly online or by phone.
- Consistency beats occasional lump sums. A smaller amount paid every month compounds its effect faster than the same total amount paid once a year, because it starts reducing interest sooner.
Frequently asked questions
Not automatically. Paying extra on a loan is a guaranteed return equal to your interest rate. If you could realistically earn more investing that money elsewhere, investing may come out ahead — but “guaranteed” versus “possible” is a real trade-off worth thinking through, not just a math problem.
Biweekly payments (half your monthly payment, every two weeks) result in 26 half-payments a year — the equivalent of one extra full monthly payment annually, without it feeling like a separate expense. It’s effectively a mild, automatic version of what this calculator shows.
Generally, extra money should go toward whichever debt has the highest interest rate first — mortgages are often the lowest-rate debt someone holds, so credit cards or personal loans usually deserve the extra dollar before a mortgage does.
Usually not automatically — your required minimum payment typically stays the same, but you finish paying the loan off sooner. Some lenders offer to “re-amortize” and lower your required payment instead, but that gives up most of the interest savings, so it’s rarely the better choice.
Want to see your full monthly payment breakdown first?
Try the EMI Calculator or Debt Payoff Calculator next.
EMI Calculator Debt Payoff Calculator Back to Toolkit