See how extra payments cut years and interest off your mortgage
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.
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.
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.
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.
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.
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This calculator shows the two numbers that really matter when you throw extra money at a mortgage: how many years you shave off the loan and how much total interest you avoid paying. It then puts those savings up against what the same money would have earned in an investment account, so you can see whether paying down the mortgage is actually the better move for your rate.
On a 30-year loan at 6.5%, about 71% of your first payment is interest. Every dollar of extra principal applied in Year 1 wipes out the ~6.5% interest it would have accrued for the next 29 years. That's why an extra $100 in Year 1 saves roughly the same as $300 in Year 20.
Standard monthly P&I:
Each month, the lender collects interest first (Balance × c) and whatever's left reduces the principal. Any extra you pay goes 100% to principal, so next month's interest is calculated on a smaller balance — the compounding engine, run in reverse.
Paying extra principal earns you a guaranteed, risk-free return equal to your mortgage rate. If your rate is 7.5% and you'd otherwise invest in a high-yield savings account at 4.5%, paying down the mortgage wins every time. If your rate is 3.25% (think 2020 refinance) and you'd invest in a diversified portfolio you believe averages 7–9%, investing the difference almost always wins over long horizons. The calculator shows both scenarios on the same chart so you can see the crossover for your rate and expected return.
Yes, in most cases. Paying half your mortgage every two weeks results in 26 half-payments per year, which is the equivalent of 13 full monthly payments — one extra each year. That typically shaves 4–6 years off a 30-year mortgage and saves tens of thousands in interest, without any change to your monthly budget.
If your mortgage rate is higher than your expected after-tax investment return, paying it down wins. If your rate is lower and you're comfortable with market risk, investing usually wins long-term. The calculator shows both scenarios side by side so you can see the crossover for your specific rate and expected return.
On a typical $300,000, 30-year loan at 6.5%, paying an extra $200/month pays the loan off about 5 years early and saves roughly $70,000 in interest. The exact numbers depend on your rate and remaining balance — the calculator computes it for your inputs.
Extra payments shorten the term but keep the required monthly payment the same. A recast re-amortizes the loan over the original term after a lump-sum payment, which lowers your required monthly payment but keeps you paying for 25–30 years. Choose extra payments to be debt-free faster; choose recast to free up monthly cash flow.
No. Extra payments reduce the principal balance (and therefore the total interest and loan length), but your required monthly payment stays the same unless you recast. If lower monthly payments are your goal, ask your servicer about recasting.