Mortgage Calculator with Extra Payments

The math that makes extra payments famous

Take a $320,000 loan at 6.5% for 30 years. The required payment is $2,023 a month and the loan costs $408,143 in interest. Add $200 a month of extra principal and the loan ends in about 23 years 11 months — 73 months early — with interest of roughly $298,991. You save about $109,152 by paying 10% more each month. The schedule above shows exactly where every dollar goes, with your start date, so you can see the balance bend downward.

How is this different from the payoff calculator?

This page plans a new loan: price, down payment, rate and term, with extra payments from the first month. If you already have a mortgage and know your current balance and payment, the mortgage payoff calculator is the sharper tool — it also handles one-time lump sums. Both use the same amortization engine; pick by where you are in the journey.

Three ways to structure the extra

• Fixed extra monthly (modeled here): simple, automatic, and the savings compound because early dollars kill the most interest.
• Biweekly halves: paying half the payment every two weeks adds one full extra payment a year — see the biweekly calculator for its specific savings.
• Annual lump sums: bonuses or tax refunds applied once a year. Nearly as effective if applied early in the year, every year.

Before you commit to extra payments

Extra principal is illiquid — you cannot easily withdraw it later. Most households should first hold 3–6 months of expenses in cash, capture any employer retirement match, and clear debts that cost more than the mortgage rate. After that, extra principal earns a guaranteed return exactly equal to your mortgage rate. More strategy in our guide on paying off a mortgage early.