This interest portion of payment calculator shows how much of a loan payment goes to interest versus principal, from the current balance and rate. Enter the values above.
Formula
Interest part = Current balance × (rate ÷ 12) Principal part = Payment − Interest part
Example
Balance $20,000 at 7%: interest part = 20,000 × 0.07/12 = $116.67; the rest of the payment reduces principal.
Good to know
These results are estimates for educational purposes only and are not financial advice. Rates, fees, and terms vary — confirm figures with a licensed professional before making decisions. Last updated: August 2026.
Frequently Asked Questions
How do I find the interest part of a payment?
Multiply the current balance by the monthly rate. The remainder of the payment goes to principal.
Why is early interest so high?
Because interest is charged on the full outstanding balance, which is largest at the start of the loan.
How does the split change over time?
As principal falls, the interest part shrinks and more of each payment reduces the balance.