See how much time and interest you save by making extra principal payments on your mortgage.
How much sooner will I pay off my mortgage if I add $200 a month? On a $250,000 balance at 6.5% with 25 years left, that extra $200 ends the loan 66 months early and saves about $64,928 in interest. The page also takes a one-time lump sum, such as a bonus or tax refund, and sets the original schedule beside the accelerated one so you can compare them directly.
Take the default inputs: $250,000 remaining, 6.5% rate, 25 years left, $200 extra each month. The original schedule needs 300 payments of $1,688.02 and accrues $256,405.37 in interest. With the extra $200 the loan is gone after 234 payments, which is 19 years and 6 months, and interest falls to $191,477.49. The difference is 66 months and $64,927.88.
The $1,688.02 comes from the standard payment formula, M = B × r × (1 + r)^n ÷ ((1 + r)^n − 1), where B is the balance, r = 6.5% ÷ 12 = 0.0054167 and n = 25 × 12 = 300. It is rebuilt from the balance and remaining term you type, so it can differ from your servicer's figure.
Each month the calculator does three things. Interest for the month is balance × r, principal is M − interest, and then the extra amount comes off the balance on top of that principal. The loop stops when the balance hits zero, and the last payment is trimmed so nothing is overpaid. A lump sum is applied once, in the first month. A rate of exactly 0 falls back to balance ÷ months.
Months saved is original months minus new months, and interest saved is original interest minus new interest. For comparison, a one-time $10,000 with no monthly extra saves 27 months and $36,746.77, while $200 a month plus the $10,000 saves 83 months and $88,530.71. Figures are rounded only when displayed.
Yours. The page rebuilds a payment from balance, rate and remaining term, and it leaves out escrow for tax and insurance. If your real principal-and-interest payment is higher than the rebuilt one, you are already paying ahead and the true payoff will land earlier than the Original Schedule box says.
The model assumes yes, until the loan ends. Skipped months shrink the savings. The lump sum is modeled only in month one, so the same money paid in year five would save less, since five years of interest would already have accrued.
The page cannot answer that. Extra principal earns a guaranteed return equal to your mortgage rate, 6.5% here, with no market risk, but it also locks the cash inside the house. Your emergency fund, other debts and tax situation all belong in that decision.
No. A recast re-amortizes the lower balance and cuts the required payment. This tool keeps the payment fixed and lets the term shrink instead, which is why it shows a shorter timeline rather than a smaller bill.
The result will be wrong in a way that looks plausible. Ten years into a 30-year loan, the correct entry is 20 years. Using 30 stretches the payment schedule and makes the extra payment look more powerful than it is.