Home & Debt calculator
Mortgage Acceleration Calculator
How much sooner could the mortgage end, and how much interest might extra principal save?
What this tool helps you answer
How much sooner could the mortgage end, and how much interest might extra principal save?
An extra mortgage payment changes both the outstanding principal and every later interest charge. This calculator rebuilds the loan month by month, compares the scheduled path with the extra-payment path, and shows the estimated time and interest saved without mixing escrow, property tax, or insurance into the loan math.
Transparent method
How the estimate works
See how the estimate is calculated
Calculate the fixed monthly principal-and-interest payment from the current balance, annual interest rate, and remaining term.
Amortize the scheduled loan monthly by adding interest on the outstanding balance and subtracting the required payment.
Apply any one-time payment directly to principal, add the recurring extra principal each month, and compare the resulting payoff period and total interest with the original schedule.
What to check before acting on the result
How to read it
- Confirm the current principal balance, rate, and remaining term from the latest statement.
- Tell the servicer to apply extra money to principal rather than a future payment.
- Keep emergency liquidity and other financial priorities in view before accelerating the loan.
Not included
- Adjustable rates, interest-only periods, balloon payments, or loan modifications
- Escrow, property tax, homeowners insurance, mortgage insurance, or association dues
- Prepayment penalties, recast fees, late charges, or lender posting conventions
- Investment returns, tax deductions, inflation, or a recommendation to prepay
Common questions
Frequently asked questions
Does an extra mortgage payment reduce principal?
It can when the servicer applies it as an additional principal payment. Confirm the lender’s instructions and review the next statement.
Why does paying principal early save interest?
Future monthly interest is calculated on a smaller balance, so more of each later payment goes to principal and the loan can end sooner.
Does this include escrow in the payment?
No. The calculated payment is principal and interest only. Taxes, insurance, mortgage insurance, and other escrow items do not reduce the loan balance.
Should I pay the mortgage or invest instead?
That decision depends on liquidity, risk, taxes, time horizon, other debt, and the value you place on reducing a guaranteed borrowing cost. This tool only calculates the loan path.
Sources
Rules and references behind this calculator
Want the fine print? See sources, methods, and limits.