Budget a home purchase or refinance
Estimate the monthly housing cost, then test payment and refinance choices.
Mortgage Extra Payment Calculator
Estimate interest savings and payoff timeline acceleration from extra monthly or annual mortgage principal payments under a fixed-rate monthly-amortization model.
Live
Parameters
R Reset
Presets
$320,000.00
$10,000.00$10,000,000.00
$
25
140
Analytics Dashboard
Total Interest Saved
Excellent$69,081.86
Standard Monthly Payment$2,160.66
Accelerated Payoff Time20 yrs 6 mos
Time Saved Off Loan4 yrs 6 mos
Significant Interest CompressionMinimize lifetime interest expenses
Compare the modeled savings with your liquidity needs and confirm principal-payment instructions with your servicer.
The modeled strategy yields at least $25,000 in interest savings under the entered assumptions.
InterpretationHigher modeled savings: at least $25,000 less interest under the entered assumptions. Significant Interest Compression: The modeled strategy yields at least $25,000 in interest savings under the entered assumptions.
How to Use the Mortgage Extra Payment Calculator
Extra payments applied to principal reduce the balance used to calculate later monthly interest and can shorten the payoff timeline. Use this calculator to compare a fixed-rate principal-and-interest schedule with extra monthly payments or an annual lump sum.
Input variables:
- Current Loan Principal ($): The remaining unpaid principal balance on your mortgage.
- Interest Rate (%): Your current annual interest rate.
- Remaining Term (Years): The remaining length of your mortgage in years.
- Extra Monthly Payment ($): Additional monthly principal contribution made alongside standard payment.
- Annual Lump-Sum Prepayment ($): One-time extra principal payment contributed once every 12 months.
Mortgage Amortization Explained: How Payments, Principal & Interest Work
Master the mathematics of home loan amortization, learn how monthly PITI outlays work, understand PMI rules, and optimize your payoff strategy.
Read Full Guide →Mortgage Worked Example Pack: 5 Real-World Scenarios
Step-by-step mathematical walkthroughs of 30-year fixed, 15-year accelerated, extra prepayment payoff, refinance break-even, and low down payment PMI scenarios.
Read Full Guide →Refinance Break-Even Decision Guide: When Does Refinancing Pay Off?
Learn how to calculate your refinance break-even period, evaluate upfront closing costs, avoid loan term reset traps, and decide when to lock a new rate.
Read Full Guide →How do extra payments affect my monthly payment amount?
Under this calculator's no-recast assumption, extra principal payments do not change the scheduled monthly principal-and-interest payment. They reduce the modeled balance and shorten the term. A lender-approved recast or different loan terms can change the required payment.
Is it better to pay extra monthly or as an annual lump sum?
Under the same total contribution, principal paid earlier generally reduces more later interest. This calculator applies monthly extras every month and applies an annual lump sum after the scheduled payment in months 12, 24, 36, and so on. Actual results depend on servicer timing and allocation.
Universal Loan Calculator
Model payments, fees, APR, balloon balances, deferred repayment and extra-payment strategies in one calculator.
Refinance Break-Even CalculatorEstimate monthly principal-and-interest savings, cash closing-cost payback time, and undiscounted lifetime interest difference for a fixed-rate, rate-and-term mortgage refinance.
Retirement Withdrawal CalculatorEvaluate safe withdrawal rates, dynamic guardrails, and portfolio longevity during retirement. Compare the 4% rule against Guyton-Klinger and constant percentage strategies.
Savings Goal CalculatorCalculate how to achieve your specific savings goals, whether solving for required monthly deposits or the time needed.
Continue this calculation