Partially Amortized Loan Calculator

What Is a Partially Amortized Loan?

A partially amortized loan requires regular payments over a set term, but those payments are not sufficient to fully pay off the principal balance by the end of the term. Instead, a large lump sum payment — often called a balloon payment — is due at maturity to cover the remaining balance.

This structure is common in commercial real estate, equipment financing, and certain mortgage products. Borrowers benefit from lower monthly payments during the loan term, but must plan for the final balloon payment.

How the Calculator Works

This calculator uses standard amortization formulas to determine your fixed monthly payment based on the loan amount, interest rate, and amortization period. It then calculates the remaining principal balance at the end of the loan term.

The key distinction from a fully amortized loan is that the amortization period is longer than the loan term. For example, a 10-year loan amortized over 30 years uses a 30-year payment schedule, but the loan matures after 10 years — leaving a significant unpaid balance.

Input Parameters

• Loan Amount — The total principal borrowed.
• Interest Rate — The annual interest rate applied to the loan.
• Loan Term — The actual duration of the loan before the balloon payment is due.
• Amortization Period — The period over which payments are calculated (typically longer than the loan term).

How to Use This Calculator

1. Enter the total loan amount you are borrowing.
2. Input the annual interest rate as a percentage.
3. Set the loan term — the number of years until the balloon payment is due.
4. Set the amortization period — the number of years used to calculate the payment schedule.
5. Click calculate to view your monthly payment and the remaining balance at maturity.

Understanding Your Results

The calculator provides two primary outputs:

• Monthly Payment — The fixed amount due each month based on the amortization period.
• Remaining Balance — The principal still owed at the end of the loan term. This is the balloon payment amount.

Note that the monthly payment does not include taxes, insurance, or other fees. The remaining balance assumes all payments are made on time and no additional principal payments are applied.

Practical Use Cases

• Commercial Real Estate — Businesses often use partially amortized loans to keep monthly payments manageable while expecting to refinance or sell the property before the balloon payment is due.
• Equipment Financing — Companies finance equipment with a balloon structure to match the equipment's useful life and expected resale value.
• Bridge Loans — Short-term financing where the borrower plans to pay off the loan with proceeds from a future sale or refinance.

Common Mistakes to Avoid

• Confusing loan term with amortization period — The loan term is the actual duration of the loan; the amortization period determines the payment amount. They are not the same.
• Ignoring the balloon payment — A partially amortized loan requires a plan for the remaining balance. Failing to prepare for this lump sum can lead to default or forced refinancing at unfavorable terms.
• Assuming the interest rate is fixed for the entire amortization period — Some loans have adjustable rates that reset before the balloon payment is due, which can change your payment amount.

Limitations and Considerations

This calculator provides estimates based on the inputs you provide. Actual loan terms may include additional costs such as origination fees, prepayment penalties, or variable interest rates. The remaining balance calculation assumes a constant interest rate and no additional principal payments. Consult a financial professional for loan structuring decisions.