📊 Interest-Only Loan Calculator
Calculate the monthly payment during the interest-only period and the payment shock when you start repaying principal. See a full amortization schedule and compare with a standard fully-amortizing loan.
What Is an Interest-Only Loan Calculator?
An interest-only loan calculator helps you understand the payment structure of a loan where you pay only the interest for a set period, with principal payments starting later. This type of loan is common in mortgages, construction financing, and bridge loans where borrowers prioritize cash flow in the early years.
This calculator shows you:
- Interest-Only Monthly Payment , the lower payment during the IO period.
- Amortizing Monthly Payment , the higher payment after the IO period ends.
- Payment Shock , the difference between the two payments.
- Full Amortization Schedule , see every payment over the life of the loan.
How Does the Interest-Only Loan Calculator Work?
The calculator uses two formulas:
During the interest-only period, your payment covers only the interest that accrues on the outstanding principal. The principal balance does not decrease during this period.
After the IO period ends, the remaining balance is fully amortized over the remaining term. This payment is typically significantly higher because it includes both principal and interest.
Why Use This Interest-Only Loan Calculator?
- Payment Shock Analysis: See exactly how much your payment will jump when the IO period ends.
- Full Amortization: View every payment over the life of the loan.
- Compare Structures: Understand the trade-off between lower early payments and higher total interest.
- Visual Charts: See the cost breakdown and payment trajectory over time.
- Free & Private: No registration, no data storage , all calculations run in your browser.
❓ Interest-Only Loan Calculator FAQ
What is an interest-only loan?
An interest-only loan allows you to pay only the interest on the loan for a set period (typically 5-10 years). The principal balance does not decrease during this time. After the IO period ends, the loan is fully amortized over the remaining term.
What is "payment shock"?
Payment shock is the sudden increase in your monthly payment when the interest-only period ends and you start paying principal as well. The amortizing payment is typically much higher because it must pay off the full loan balance over the remaining term.
How is the interest-only payment calculated?
The interest-only payment is calculated as Loan Balance × Annual Rate ÷ 12. For example, a $300,000 loan at 6.5% would have an IO payment of $300,000 × 0.065 ÷ 12 = $1,625.
Does the principal balance decrease during the IO period?
No. During the interest-only period, none of your payment goes toward principal. The balance remains the same.
Is an interest-only loan more expensive overall?
Yes. Because you don't pay down principal during the IO period, you'll pay more interest overall compared to a fully amortizing loan with the same rate and term. However, the lower early payments can be beneficial for cash flow management.
What happens after the interest-only period ends?
After the IO period ends, the loan is fully amortized over the remaining term. Your monthly payment will increase significantly because it now includes both principal and interest.
Can I pay extra during the interest-only period?
Yes. Most interest-only loans allow additional principal payments. This can reduce the principal balance and lower the total interest cost.
How accurate is this calculator?
This calculator provides accurate results based on standard loan amortization formulas. Use it as a planning tool and consult a financial professional for specific borrowing decisions.
Is this calculator free to use?
Yes, this calculator is completely free to use. No registration or personal data storage is required. All calculations are performed in your browser.
When should I consider an interest-only loan?
Interest-only loans can be useful for investors seeking cash flow, borrowers with irregular income, or those planning to refinance or sell before the IO period ends. However, they carry higher risk and should be used carefully.