Free calculator

Extra Payment Calculator

This extra payment calculator compares a scheduled loan with the same loan plus an added monthly amount, showing the months and interest you save.

The lowest rates are only available to the most qualified applicants.

Advertising disclosure: Loancalculated may receive a referral fee if you apply through the link above. That fee does not change the rate you are offered, and it does not change our content. We are not a lender. Read the full disclosure.

By the Loancalculated Editorial Team · Last updated 2026-09-16

Enter your numbers and press Calculate. Nothing you type leaves your browser.

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The lowest rates are only available to the most qualified applicants.

Advertising disclosure: Loancalculated may receive a referral fee if you apply through the link above. That fee does not change the rate you are offered, and it does not change our content. We are not a lender. Read the full disclosure.

How this calculator works

Adding to your monthly payment sends the surplus straight to principal, which lowers the balance and the interest charged next month.

Scheduled payment: Payment = P × i ÷ (1 − (1 + i)−n).

With an extra amount E, the payment becomes payment + E and the balance is amortized until it reaches zero.

Interest saved is the scheduled interest minus the interest actually paid. If the combined payment cannot cover the monthly interest, the balance never falls.

Frequently asked questions

How does an extra payment save interest?
The extra amount reduces principal, so the balance used to compute next month's interest is smaller. Less interest builds up over the term.
How many months can I cut?
It depends on the size of the extra payment and the rate. The tool reports both the new payoff time and the months saved.
Is it better to pay extra or refinance?
Paying extra keeps your current rate and costs nothing to start. Refinancing changes the rate and term. Run both sets of numbers before deciding.
What if my extra payment is 0?
Then the results match the original schedule: no months saved and no interest saved.

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