Extra loan payment calculator
Compare payoff time and interest under additional principal payments.
Your inputs
Your results
Ready when you areYour results will appear here.
Compare two scenarios.
Run the tool, then save A or B to compare headline results and entered values. Keep currencies, periods and assumptions consistent.
Saved scenarios stay in this browser until you clear them. Reset clears the working result; it keeps saved scenarios. Use Clear saved scenarios on a shared device.
Run the tool to save your first scenario.
How it works
Compare the same fixed-rate loan with and without a constant extra monthly principal payment, using the same cent-rounded amortization engine.
Read the source reference ↗A few things to know
Assumes extra payments are permitted and applied to principal. Excludes prepayment penalties and lender-specific accrual. Payment amount stays constant until the final reduced installment.
Results use your inputs. Keep all money amounts in the same currency.
When to use this tool
See how extra principal changes payoff time and total modeled interest. The comparison keeps the original loan terms fixed.
- Compare extra payments.
- Plan a payoff scenario.
- Inspect an accelerated schedule.
How to use extra loan payment calculator
Prepare the inputs
Use balances and rates from current statements, in one currency.
Choose the settings
Enter the scenario assumptions; this tool does not fetch market rates.
Review and export
Compare the report with the actual account terms before acting.
Try the supplied example
Inputs
principal: 10000; rate: 6; years: 3; extra: 50
Result
The example adds 50 to a 304.22 regular installment and pays the balance off sooner.
What it means
Check that your servicer applies the extra amount to principal.
Common mistakes to avoid
Check how extra payments are applied
Check how extra payments are applied.
A contractual penalty can offset savings
A contractual penalty can offset savings.
Frequently asked questions
Definitions, edge cases, and practical next steps for this tool. Search all tool FAQs ↗
Is the regular payment recalculated?
No. The original installment plus extra is paid until the final reduced payment.
Does this include a prepayment penalty?
No. Check your contract and add any actual penalty separately.
Can extra be zero?
Yes, the two schedules then match.
What happens after payoff?
No further payments are modeled.
Are escrow amounts included?
No. Only principal and interest are compared.
Can I download the accelerated schedule?
Yes. The CSV lists each month’s payment, interest, principal and balance.
Are my inputs uploaded or stored?
Processing happens locally in your browser. This tool does not upload inputs. Downloads stay on your device; sharing or opening them in another service is your choice.
What should I check before using the output?
Assumes extra payments are permitted and applied to principal. Excludes prepayment penalties and lender-specific accrual. Payment amount stays constant until the final reduced installment.
Explore the topic in the blog
Sources and method
Use the references below to check definitions and platform guidance. The model’s scope and limits are explained above. Read our editorial standards.