How to use this calculator
Enter your current loan balance, annual interest rate (APR), and your required monthly payment. Then add an extra monthly payment amount to see how it changes your payoff timeline.
The calculator compares two scenarios side by side: your current payment plan versus a plan with extra payments. You'll see the exact payoff date, total interest paid, time saved, and money saved for each scenario.
How extra payments save you money
Loans use a process called amortization. Each monthly payment is split between interest and principal. In the early months, most of your payment goes to interest. Over time, as the principal balance drops, more of each payment goes toward the actual loan balance.
When you make extra payments, that money goes directly to reducing your principal. A lower principal means less interest accrues next month, which means even more of your regular payment goes toward principal. This creates a snowball effect that accelerates your payoff.
For example, on a $200,000 mortgage at 7% over 30 years, paying just $200 extra per month saves over $90,000 in interest and pays off the loan nearly 9 years early.
Common loan payoff strategies
Avalanche method: Focus extra payments on the loan with the highest interest rate first while making minimums on everything else. This saves the most money in total interest over time.
Snowball method: Pay off the smallest balance first, regardless of interest rate. Once it's gone, roll that payment into the next smallest debt. This method builds momentum and motivation through quick wins.
Bi-weekly payments: Instead of 12 monthly payments, make 26 half-payments (every two weeks). This adds up to one extra full payment per year without feeling the pinch.
Lump-sum payments: Apply tax refunds, bonuses, or windfalls directly to your loan principal. A single $2,000 lump sum early in a 30-year mortgage can save $5,000+ in interest.
Frequently asked questions
How do extra payments reduce my total interest?
Extra payments go directly toward your principal balance. Since interest is calculated on the remaining balance each month, a lower balance means less interest accrues. This creates a compounding effect — every dollar of extra principal paid today saves you interest for the entire remaining life of the loan.
Should I pay off my loan early or invest the extra money?
It depends on your interest rate. If your loan rate is higher than the after-tax return you'd expect from investing, paying off the loan is usually the better financial move. For low-rate loans (under 4-5%), investing may yield better returns — but paying off debt offers a guaranteed, risk-free return equal to your interest rate.
Does this calculator work for all types of loans?
Yes. This calculator works for any fixed-rate amortizing loan — including mortgages, auto loans, personal loans, and student loans. It assumes a fixed interest rate and standard monthly amortization. It does not account for variable rates, interest-only periods, or balloon payments.
What is amortization and why does it matter?
Amortization is the process of spreading a loan into equal monthly payments over time. In the early months, most of your payment goes toward interest. As the principal balance decreases, more of each payment goes toward principal. Understanding this helps you see why extra payments early in a loan save the most money.