📘 About This Calculator

This calculator shows exactly how much time and interest you'll save by making extra payments toward your mortgage principal. Compare strategies — extra monthly, biweekly, or a lump sum — and see whether paying down your loan actually beats investing the same cash in the market.

🎯 Strategies Compared

Extra Monthly Payment

Add a fixed amount to every monthly payment. Even $100/month on a 30-year loan can shave 3-5 years and save tens of thousands in interest.

Biweekly Payments

Pay half your monthly payment every two weeks. Because there are 26 biweekly periods, you make one extra full payment per year — a "painless" acceleration.

Lump Sum

A single one-time principal payment (e.g. tax refund, bonus, inheritance). Most effective early in the loan, when your payments are heavily interest-weighted.

Pay Off vs Invest

Compares the guaranteed "return" from saving mortgage interest against investing the same extra dollars at a market rate. Your mortgage rate is the hurdle — beat it, and investing wins.

💡 When Early Payoff Makes Sense

⚠️ When Investing Beats Payoff

🏦 Current Mortgage

Years left on the current amortization schedule
Leave at 0 to auto-calculate from balance, rate, and term

⚡ Accelerator Strategy

📊 Invest Instead?

Compare paying down the mortgage against investing the same extra dollars at a market return.

Based on S&P 500 avg annual return 2016-2025

💡 Quick Rule

If your expected after-tax investment return exceeds your mortgage rate, investing wins. If not, or if peace of mind matters, accelerated payoff is the guaranteed "return."

Savings Summary

Enter your loan details to see savings

Balance Over Time

Enter your loan details to see chart

Annual Amortization

Enter your loan details to see schedule

Payoff vs Invest

Enter your loan details to see comparison