Extra Payment Calculator
This extra payment calculator shows how a little more toward your mortgage each month can shave years off the loan. It can also save thousands in interest.
By Onias Derilus, Mortgage Capital · NMLS# 1859012 · Last Updated: June 2026
Total Interest: With vs Without Extra
Applying extra dollars to principal each month shortens the loan and removes future interest. Confirm your servicer applies extra payments to principal. Estimate only.
Every extra dollar you put toward principal removes the future interest that dollar would have generated for the rest of the loan. That is why even a modest extra payment can have an outsized effect.
The earlier you start, the bigger the impact, because there is more remaining term over which the saved interest compounds in your favor.
These figures are estimates. For neutral, official guidance on mortgage costs and what lenders can charge, see the CFPB's Owning a Home guide.
How to Use This Calculator
- 1
Enter your loan amount, rate, and original term.
- 2
Add the extra amount you could pay toward principal each month.
- 3
Review how many years come off the loan.
- 4
Check the total interest saved to decide whether the trade-off fits your budget.
The Formula & Assumptions
New payment = base P&I + extra
Each month:
balance += balance × monthly rate
balance −= new payment
Count months until balance = 0
We compute your normal principal-and-interest payment, add your extra contribution, then simulate the loan month by month until the balance reaches zero.
The interest saved is the difference between total interest on the original schedule and total interest once the loan pays off early.
Tell your servicer to apply extra payments to principal, not to prepay the next month. Confirm there is no prepayment penalty — most modern conforming loans have none.
Frequently Asked Questions
Is it better to make extra payments or refinance?
They solve different problems. Extra payments shorten the loan without changing your rate, while refinancing lowers the rate but resets the term. If rates have dropped meaningfully, compare both with the refinance calculator.
When should I start making extra payments?
As early as possible. Extra principal applied in the first years removes interest for the longest remaining period, so the same dollar saves far more early than it would late in the loan.
Will my lender penalize extra payments?
Most conforming and government loans have no prepayment penalty, but some non-QM and investor loans do. Check your note, and confirm with your servicer that extra funds are applied to principal.
Should I pay off the mortgage or invest instead?
It depends on your rate, risk tolerance, and goals. Paying down a higher-rate mortgage is a guaranteed return equal to the rate, while investing carries risk and potential upside. Consider both with a financial professional.
Ready to Turn Your Estimate Into a Real Pre-Approval?
Get a personalized rate quote and pre-approval from a licensed Florida mortgage broker, no obligation.
Rates are illustrative only. APR and payments vary by credit score, loan amount, and market conditions. Subject to credit approval. Not a commitment to lend. NMLS# 1859012. Equal Housing Lender.
It shows how making extra principal payments — monthly, yearly, or one-time — shortens your loan term. You also see how much total interest you cut.
Extra Payment Calculator in Florida
Extra-payment savings come purely from principal and interest, so the result is the same regardless of state. In Florida, though, the money you free up by paying off your loan sooner is especially valuable given rising insurance costs that you will still owe even after the mortgage is gone.
How the Extra Payment Calculator Works
The calculator runs your loan on two tracks: the standard schedule and a schedule with your extra principal applied. It compares the two to show the months saved and the interest saved by paying ahead.
The Extra Payment Formula, Explained
Each extra dollar reduces the balance, so future interest = lower balance × rate
Extra payments work because mortgage interest is charged on the outstanding balance. Every dollar of extra principal permanently removes future interest. That dollar would have generated interest for the rest of the loan.
The effect compounds over time. Extra payments made early in the loan save far more than the same amount paid near the end. The calculator quantifies both the time saved and the dollars saved.
The Complete Extra Payment Calculator Guide
Paying extra toward principal is one of the few guaranteed returns in personal finance: you save the exact interest rate on your loan, tax-free. On a 7% mortgage, an extra payment effectively earns 7%, which is hard to beat with low-risk alternatives.
Timing magnifies the benefit. Because early balances are largest, extra payments in the first decade of a 30-year loan save dramatically more interest than the same payments made later. Front-load if you can.
Confirm your lender applies extra funds to principal, not to future payments, and check for any prepayment terms. The calculator assumes every extra dollar reduces the balance immediately, which is how most modern mortgages work.
Extra Payment Calculator FAQ
Is it better to pay extra monthly or once a year?
Both help. Monthly extra payments reduce the balance a little sooner each period, while a lump sum has a larger immediate effect. The calculator lets you compare the two for your loan.
Should I pay extra or invest instead?
Paying extra guarantees a return equal to your mortgage rate. Investing may earn more but carries risk. Many borrowers split the difference, especially when the mortgage rate is high.