Interest-Only Mortgage Calculator
Last updated: July 2026
Estimate the initial interest-only payment, later principal-and-interest payment and total interest for an interest-only mortgage.
Initial interest-only payment
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- Later principal-and-interest payment: —
- Payment increase after interest-only period: —
- Estimated total interest: —
- Principal remaining after interest-only period: —
On this page
Quick summary: Estimate the initial interest-only payment, later principal-and-interest payment and total interest for an interest-only mortgage. Enter the requested values, calculate, review the result, and compare more than one realistic scenario before making a decision.
Read the complete guide
What this calculator estimates
Estimate the initial interest-only payment, later principal-and-interest payment and total interest for an interest-only mortgage. It is designed for fast planning and comparison in the United States. The output is an estimate, not a binding quote, approval, tax determination, insurance offer or professional recommendation.
How to use it
Enter the requested values using a single consistent time period and currency. Select Calculate, review the headline result and supporting figures, then change one assumption at a time to compare another scenario.
How the calculation works
During the interest-only period, the monthly payment is the loan balance multiplied by the monthly interest rate. The remaining balance is then amortized over the months left in the original term.
Important limitations
Many interest-only loans have adjustable rates, balloon provisions or qualification rules that are not modeled. Taxes, insurance, fees and prepayment terms are excluded.
Frequently asked questions
Is the result exact?
No. It is a planning estimate based on the assumptions entered.
Can I compare different scenarios?
Yes. Change one input at a time so you can see which assumption changes the result.
Does the calculator store my inputs?
The calculation runs in the browser and does not require an account. Avoid entering unnecessary confidential information.