Instead of asking "what if I pay extra," this calculator flips it: pick the year you want to be mortgage-free, and it tells you the exact extra monthly principal to hit that target. Great tool for planning payoff around retirement, kids' college, or a major life milestone.
Worked example: $280,000 remaining balance, 6.5% rate, 24 years left on original schedule. You want to be paid off in 15 years (before kids graduate high school). The calculator says: add $628/month extra principal. Total interest saved vs. staying on the 24-year schedule: $134,000.
Set the right target year
- Retirement year. Most common goal. Own the home free and clear before your income drops.
- Kids finish college. Frees cash flow during late-career earning.
- Age 50 or 55. Gives you flexibility for career changes, sabbaticals, or early retirement.
- Before a planned move. If you plan to sell in 12 years, accelerating payoff to year 12 maximizes equity at sale.
Is early payoff worth it vs investing?
Depends on your mortgage rate and your expected investment return. At a 7% mortgage rate, extra payoff earns a guaranteed 7% tax-free. The S&P has averaged 10% long-term but with volatility and taxes the risk-adjusted return is comparable. In a 7%+ rate environment, mortgage payoff is competitive. In a 3-4% rate environment, investing wins clearly.