Mortgage Payoff Calculator (Extra Payment)
See how much time and interest an extra monthly mortgage payment saves you. Enter your balance, rate, and remaining term to find your new payoff date and total interest saved.
- Data verified · July 2026
- Edited by Martín Rodríguez
- Formula verified by automated tests
- Private — runs on your device
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How to use this calculator
Follow this tool’s steps, then review its formula, assumptions, and limits below.
Enter your current balance, your interest rate (APR), the years remaining, and the extra amount you can pay each month. The tool builds your normal amortization schedule, then re-runs it with the extra payment applied straight to principal, and compares the two — new payoff date, months saved, and total interest saved.
The results are often striking. Because a mortgage front-loads interest, even a modest extra payment early in the loan can save tens of thousands of dollars. Use it to decide whether to round up your payment, make a 13th payment each year, or throw a bonus at the loan — and to weigh paying down the mortgage against investing the same money.
When to use this calculator
- See how much interest an extra $100, $200, or $500 a month would save.
- Find your new mortgage-free date after committing to extra payments.
- Decide whether to round your payment up to the next $100.
- Estimate the payoff impact of applying a tax refund or bonus to principal.
- Compare the savings of extra payments early vs later in the loan.
- See total interest on your remaining term if you change nothing.
- Plan a goal to be mortgage-free before retirement.
- Weigh paying down a 7% mortgage against other debts.
- Check how a biweekly-style extra payment shortens a 30-year loan.
- Model an aggressive payoff to clear the loan in half the time.
Extra payment savings on a $300,000 mortgage at 6% (30 years left)
| Extra per month | New payoff time | Interest paid | Interest saved |
|---|---|---|---|
| $0 | 30 years | $347,515 | — |
| $100 | 26 yr 1 mo | $294,000 | ~$53,000 |
| $200 | 23 yr 3 mo | $256,000 | ~$91,000 |
| $300 | 21 years | $228,000 | ~$120,000 |
| $500 | 17 yr 8 mo | $187,000 | ~$160,000 |
Illustrative figures for a $300,000 balance at 6% APR with 30 years remaining. Your results depend on your balance, rate, and term. Principal and interest only.
How it works
How extra payments save money
Monthly payment (P&I) = Balance × r / (1 − (1 + r)^−n) where r = APR ÷ 12
Each month: interest = balance × r; the rest of your payment reduces principal.
Extra payment → principal drops faster → less balance to charge interest on.Because interest is charged on the outstanding balance, cutting the balance faster removes interest from every remaining month. Early in a mortgage, most of your payment is interest — so extra principal then has the biggest effect.
Extra payment impact — $300,000 at 6%, 30 years
| Extra per month | Payoff time | Interest paid | Interest saved |
|---|---|---|---|
| $0 | 30 years | ~$347,515 | — |
| $100 | ~26 yr 1 mo | ~$294,000 | ~$53,000 |
| $200 | ~23 yr 3 mo | ~$256,000 | ~$91,000 |
| $500 | ~17 yr 8 mo | ~$187,000 | ~$160,000 |
(Figures rounded; your loan's exact numbers depend on rate and balance.)
Why timing matters
An extra $200/month applied in year 1 of a 30-year loan saves far more than the same $200 applied in year 20, because there is more interest left to eliminate. The best time to start is as early as possible.
Should you pay down or invest?
| Consideration | Favors paying the mortgage | Favors investing |
|---|---|---|
| Interest rate | Higher rate (6–8%) | Lower rate (3–4%) |
| Risk tolerance | Guaranteed 'return' = your rate | Comfortable with market risk |
| Tax | You don't itemize mortgage interest | You have tax-advantaged space (401k, IRA) |
| Peace of mind | Value being debt-free | Value liquidity/flexibility |
Paying extra earns a guaranteed return equal to your mortgage rate. Investing may earn more over time but carries risk and is less liquid.
Before you commit
Disclaimer
Educational tool. It models principal and interest only and assumes a fixed rate and consistent extra payments. It does not include taxes, insurance, PMI, or fees. Confirm your actual figures with your loan servicer.
Example: $300,000 balance, 6% rate, 30 years left, +$200/month
Frequently asked questions
How much interest can I save with extra mortgage payments?
Does an extra payment go to principal automatically?
Is it better to pay extra monthly or make one lump sum?
What is a biweekly mortgage payment?
Are there penalties for paying off my mortgage early?
Should I pay off my mortgage or invest instead?
Does this include property taxes and insurance?
Will extra payments lower my monthly payment?
Sources & references
Methodology & trust
Finance calculator with its formula verified automatically against CFPB — Understand loan options (mortgages), per our editorial policy and methodology.
Updated: July 2026. Parameters are verified periodically against the cited sources.
Calculations run 100% in your browser. We do not store or transmit your data.
Indicative results. For critical decisions, consult a professional.
Rodríguez, M. (2026). Mortgage Payoff Calculator (Extra Payment). Hacé Cuentas. https://hacecuentas.com/en/mortgage-payoff-extra-payment-calculator
Content licensed under CC-BY 4.0 — reuse it citing the source with a link to Hacé Cuentas.