Extra loan payment calculator
Compare monthly overpayments and a lump sum while keeping your normal loan payment unchanged.
No account needed · Financial inputs are calculated in your browser · Example values shown
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Understand the assumptions
These are estimates from the values you enter. Review the assumptions in your report and check the actual terms before making a financial commitment.
How this calculator works
See how additional principal payments affect the time and interest needed to repay a fixed-rate loan. Compare no extra payment, a recurring monthly amount, an immediate lump sum and both together.
Example: $100,000 at 6% for 30 years
The scheduled payment is about $599.55 per month. Adding $100 each month reduces the modeled term from 360 to 252 months and saves about $39,900.25 in interest. A $10,000 immediate lump sum instead reduces it to 279 months and saves about $38,921.23.
Does a lump sum lower my scheduled payment?
This calculator preserves the original scheduled payment, so the loan ends earlier. A lender-approved recast that changes the required payment is a different calculation.
Before entering your numbers
For an existing loan, use the current balance and a remaining term that reproduces your scheduled payment. The tool derives that payment from the entered balance, rate and term; it cannot model every existing contract. It assumes extras reduce principal, the lump sum is paid immediately, and there are no early-repayment charges.
Read the monthly extra payment versus lump sum comparison or compare two new loan offers.
Frequently asked question
Does the monthly-extra versus lump-sum comparison use equal cash amounts?
Not necessarily. The recurring extra payment continues until payoff, while the lump sum is paid once at the start. Read the cash commitment as well as interest savings; the larger saving alone does not prove a better use of the same budget.