Interest Only Payment Calculator

Understand interest-only loans with clear payment and fee estimates. Test frequencies, reserves, and future amortization. Export schedules quickly for reviews, planning, and lender conversations.

Calculated Results

Payment Graph

Interest-Only Schedule

Payment #	Due Date	Interest	Fee	Reserve	Total Payment	Balance	Cumulative Interest

Calculator Inputs

Loan Amount

Annual Interest Rate (%)

Payment Frequency

Interest-Only Period (Months)

Servicing Fee Per Payment

Taxes or Insurance Reserve Per Payment

Upfront Fee

Future Amortized Rate (%)

Future Amortized Term (Months)

Day Count Basis

Schedule Start Date

Display Precision

Example Data Table

Loan Amount	Rate	IO Months	Frequency	Fee Per Payment	Reserve Per Payment	IO Payment	Future Amortized Payment
250,000.00	6.50%	60	Monthly	12.00	180.00	1,546.17	1,919.28
425,000.00	7.10%	36	Monthly	18.00	240.00	2,772.58	3,642.90
90,000.00	5.90%	24	Quarterly	20.00	0.00	1,347.50	3,993.31

This table shows sample scenarios using the same formulas applied by the calculator.

Formula Used

Periodic interest-only payment = Principal × (Annual Interest Rate ÷ Periods Per Year)

Total periodic payment = Periodic Interest + Servicing Fee + Reserve Per Payment

Total interest during interest-only period = Periodic Interest × Number of Interest-Only Payments

Daily interest estimate = Principal × Annual Interest Rate ÷ Day Count Basis

Future amortized payment = P × [r ÷ (1 − (1 + r)⁻ⁿ)]

In the amortized formula, P is principal, r is periodic rate, and n is number of future amortized payments.

This structure helps compare the lower initial payment against the later fully amortized payment after the interest-only period ends.

How to Use This Calculator

Enter the loan amount and annual interest rate.
Select how often payments are made.
Enter the interest-only period in months.
Add any recurring fee and reserve amount per payment.
Enter any upfront fee charged at closing or setup.
Provide the future amortized rate and term for post-interest-only comparison.
Choose a day-count basis for daily interest estimation.
Select a schedule start date and click calculate.
Review the summary, schedule, graph, and exported files.

FAQs

1. What is an interest-only payment?

An interest-only payment covers accrued interest without reducing principal. During that period, the balance usually stays unchanged unless you choose to pay extra principal separately.

2. Why does the later payment often rise sharply?

Once the interest-only phase ends, the same principal must be repaid over fewer remaining periods. That compresses repayment time and usually increases each scheduled payment.

3. Does this calculator include fees and reserves?

Yes. It adds a servicing fee and an optional reserve amount to each periodic payment. It also includes an upfront fee in total cash outflow calculations.

4. What does the day-count basis change?

It changes the daily interest estimate. Some lenders use 360 days and others use 365. This can slightly affect per-day accrual comparisons.

5. Does the balance fall during the interest-only period?

Not in a standard interest-only structure. The scheduled payment normally covers interest only, so the principal balance remains the same until amortization begins.

6. Can I compare future amortized payments here?

Yes. Enter a future rate and amortized term. The calculator estimates the later payment so you can compare affordability before and after the interest-only window.

7. Is this calculator useful for commercial and personal lending?

Yes. The formulas work for many loan types. Always confirm your lender’s exact compounding rules, fees, reserves, and schedule conventions before relying on a final figure.

8. What should I export to review options with a lender?

Export the CSV for spreadsheet analysis and the PDF for sharing a clean summary. Both exports help document assumptions and compare scenarios consistently.