See how extra payments slash your interest and fast-track your debt freedom date.
A loan payoff calculator shows you exactly how much interest you will save — and how many months sooner you will be debt-free — when you make extra payments on top of your regular monthly amount. Every dollar you pay beyond the minimum goes directly to reducing your principal balance. Because interest is charged on the outstanding principal, a lower balance means less interest in every future month. That compounding benefit is why even a modest extra payment can slash years off a 30-year mortgage or thousands of dollars off a student loan.
This calculator works for any fixed-rate amortizing loan: mortgage, auto loan, personal loan, student loan or home equity loan. Enter your current remaining balance, annual interest rate, remaining term in years, and how much extra you can afford to pay each month. The tool runs two full amortization schedules — one at your standard payment and one with the extra amount — and reports the difference in total interest paid and months saved.
When you take out a loan, your lender sets a fixed monthly payment using the amortization formula so that equal payments over the term will fully repay both principal and interest. In the early months of a loan, most of each payment covers interest with very little going to principal. As the balance falls, the interest portion shrinks and the principal portion grows.
If you add even $100 extra to a monthly payment, all of it reduces principal immediately. That lower balance means next month's interest charge is smaller, so a slightly larger share of your regular payment also hits principal. The benefit compounds quietly but powerfully over time.
| Loan | Extra/mo | Interest saved | Months saved |
|---|---|---|---|
| $300,000 mortgage · 6.5% · 30yr | $200 | ~$63,000 | ~72 |
| $30,000 auto loan · 7% · 5yr | $100 | ~$820 | ~7 |
| $20,000 student loan · 5.5% · 10yr | $75 | ~$1,900 | ~14 |
| $15,000 personal loan · 12% · 5yr | $150 | ~$2,100 | ~16 |
Estimates based on standard amortization. Actual savings may vary with payment timing and lender policies.
If your required payment is $847, pay $900. You will barely notice the difference in your monthly budget, but the extra $53 consistently applied to principal adds up to significant savings over the life of a loan. Use this calculator to see exactly how much your round-up saves.
Instead of making one full monthly payment, pay half the amount every two weeks. There are 52 weeks in a year, so you end up making 26 half-payments — equivalent to 13 full payments instead of 12. That one extra payment per year reduces a 30-year mortgage by roughly 4–5 years with zero lifestyle change required. Check with your servicer that they accept biweekly payments and apply the extra to principal.
Tax refunds, bonuses, gifts and side-income windfalls are perfect for one-time lump-sum principal payments. A single $2,000 payment on a 6.5% mortgage saves roughly $6,800 in interest over the remaining term. Call or log into your loan portal and specify the payment is for "principal only" — if you do not specify, the servicer may apply it to future regular payments instead.
If interest rates have dropped or your credit score has improved, refinancing a 30-year mortgage into a 15-year loan dramatically cuts total interest. A $300,000 loan at 7% for 30 years costs about $419,000 in total payments; the same loan at 6% for 15 years costs about $455,000 total — but you pay $36,000 less interest and own the property in half the time. Factor in closing costs (typically 2–5% of the loan amount) when weighing this option.
If you have multiple loans, direct extra money to the highest-interest loan first. Once it is paid off, roll its full payment into the next-highest-rate loan. This "avalanche" approach minimises total interest paid across your debt portfolio. An alternative is the "debt snowball" — paying the smallest balance first — which provides motivational milestones but typically costs more in interest.
This is the most important question for anyone with extra cash each month. The break-even point is your loan's interest rate. If your loan charges 7% and you expect a broad-market index fund to return 7% annually (the common long-run estimate for US equities), you are roughly indifferent between the two options. If your loan rate is above 7%, paying down debt is the guaranteed equivalent of earning that rate risk-free. If your rate is below 4–5%, investing the difference may generate better long-term wealth — especially in a tax-advantaged account like a 401(k) or Roth IRA.
High-interest consumer debt (credit cards at 18–24%) should almost always be paid off before investing outside a tax-advantaged account. For mortgages at current rates of 6–7%, the calculus is closer; personal risk tolerance matters.
Before making large extra payments, read your loan agreement. Most personal, auto and student loans in the US have no prepayment penalty. Mortgages originated before 2014 may have a "prepayment penalty" clause that charges a fee — often 2% of the remaining balance — if you pay off the loan within the first 3–5 years. Mortgages originated after the Dodd-Frank Act's Qualified Mortgage rules generally do not carry prepayment penalties. If you are unsure, call your servicer and ask directly.
Loan balance: Your current outstanding principal, not the original loan amount. Find it on your most recent statement or online account.
Annual interest rate: The rate on your current loan, not the APR (which includes fees). Use the interest rate field from your statement.
Remaining term: The number of years left, not the original term. If you took a 30-year mortgage 7 years ago, enter 23.
Extra monthly payment: The additional amount you plan to add each month. Even $25 is worth calculating — you may be surprised by the result.
Even $50–$100 extra per month can save thousands in interest and cut years off a loan term, because the extra amount goes directly to principal.
Extra payments reduce your outstanding principal, which lowers the interest charged in every future month — creating a compounding benefit.
Some mortgages have a prepayment penalty in the first 3–5 years. Personal, auto and student loans rarely do. Check your loan agreement before making large extra payments.
Avalanche: pay extra on the highest-rate debt first (saves most interest). Snowball: pay extra on the smallest balance first (motivational wins). Both work — avalanche is mathematically optimal.
If your loan rate is higher than expected investment returns (~7% for index funds), pay down debt first. If your rate is lower, investing may produce better long-term results.
Paying half your monthly payment every two weeks results in 26 half-payments (13 full payments) per year instead of 12, effectively adding one extra payment annually.
Yes. Enter any remaining balance, rate and term. It works for mortgage, auto, personal or student loans — any fixed-rate amortizing loan.
The calculator runs two amortization schedules: one at the regular payment and one with the extra amount added. The difference in total interest paid is your saving.