Every extra dollar hits principal directly — a fixed, predictable return equal to your mortgage rate.
When sending extras, instruct your servicer in writing: “apply to principal.” Otherwise payments may sit as advance credit for future due dates with zero benefit.
Enter balance, rate, and remaining term.
No valid data — load a sample to preview.
Fast calculator execution with private inputs, clear estimates, and responsive layouts across desktop and mobile.
Salary, tax, savings, and career planning values are processed locally wherever possible. No account or saved calculation history is required.
Update inputs and see planning results immediately, without waiting for signups, dashboards, or checkout flows.
Works across modern desktop and mobile browsers so salary, tax, and savings calculations remain usable on any screen size.
Because mortgages amortize, early payments attack principal directly, shrinking every subsequent interest charge. This calculator runs two parallel amortizations, baseline versus extra-payment, and reports months saved, interest eliminated, and the new payoff date. Inspect the schedule row-by-row with our amortization calculator.
Homeowners with surplus cash flow deciding between prepayment and investing, borrowers carrying PMI who want to cross the 20%-equity threshold faster, and anyone approaching retirement wanting the home 'burned' beforehand. First ensure your emergency fund is solid.
Example Input
Balance: $320,000 at 6.5%, 28 years remaining. Extra: $100/month.
Sample Output
Payoff accelerates by roughly 3 years 8 months and saves about $63,000 in interest, a projected 6.5% return (based on current rates) on every extra dollar.
Example Input
Same loan with $500/month extra.
Sample Output
Paid off ~11 years sooner with roughly $135,000 interest avoided, freeing the full payment for investing a decade earlier, a FIRE-acceleration lever shown in our [FIRE guide](/blog/fire-movement-explained/).
After a raise or bonus lands, when refinancing is unattractive because current rates are lower than yours (then prepayment beats refi), when comparing projected 6.5% 'returns' (based on current rates) versus market risk, and when modeling biweekly-payment equivalents.
We amortize at your rate over the remaining term, then recompute with the extra amount added to principal monthly until zero. Results assume fixed rate, consistent extras, and no prepayment penalties. Specify extra dollars rather than rounding games for cleanest comparisons.
Sending extra money without the 'apply to principal' instruction lets servicers park it as future-payment credit. Liquidity matters: home equity is trapped unless you sell, borrow, or use a HELOC, unlike a brokerage balance. And at sub-4% legacy rates, tax-advantaged investing often mathematically beats prepayment.
Prepayment earns a relatively low-risk return equal to your mortgage rate. Above ~6% rates, that competes strongly with expected market returns. Below ~4%, tax-advantaged investing usually wins mathematically. Personal peace-of-mind value is real and legitimate either way.
They are nearly identical: biweekly creates one extra full payment yearly. Self-directing one extra monthly payment achieves the same result with more flexibility, and pauses easily during tight months. Verify any third-party biweekly service is not charging unnecessary fees.
Diversified portfolios have historically produced returns that differ from a mortgage rate, but future market performance is uncertain. The trade-off is investment risk and sequence-of-returns risk versus the interest savings from prepayment. Many planners suggest capturing employer matches, using tax-advantaged accounts where appropriate, then comparing both goals.
Zero-friction browser math with no signup walls, working identically across desktop and mobile browsers. Drag extra-payment amounts upward and watch interest savings jump nonlinearly, then lock in a plan your budget sustains.
Follow this 3-step planning sequence to compare the current calculator with the next useful financial or career check.
Current calculation completed with your latest planning inputs.
Compare true total cost of leasing versus buying, including depreciation, financing, fees, and equity.
Access all salary, tax, and career calculators in one unified hub.
Pair this calculator with related tools to compare salary, tax, savings, and career outcomes.
Calculate your monthly mortgage payments including principal, interest, taxes, and insurance.
Create an estimated loan payment and amortization schedule with optional extra payments.
Calculate your monthly savings, break-even timeline, and total lifetime interest savings when refinancing your mortgage.
Decide whether paying discount points to lower your rate pays off before you sell or refinance.
Estimate monthly deposits and milestones needed to reach your target savings goals with compound growth.
Calculate maturity returns, APY yield, and interactive rotating CD ladder strategies for liquidity and yield.
Discover estimate how much house you can afford without risking financial stress. We break down DTI ratios, the 28/36 rule, closing costs, property taxes, and down payment guidelines across US, UK, Canadian, and Australian housing markets.
Explore our dedicated calculators to systematically plan your career, estimate taxes, and manage your financial growth.