Partially Amortized Loan Calculator
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The Partially Amortized Loan Calculator helps commercial real estate investors, business buyers, and lenders calculate monthly payments and remaining final balloon payments for partially amortized loans (balloon loans). Common in commercial mortgages and seller financing, these loans calculate monthly payments based on a longer amortization period (e.g., 25 or 30 years) while requiring full principal payoff at an earlier maturity date (e.g., 5 or 10 years).
The Partially Amortized Loan Formula
Monthly payments are computed using a long-term amortization period, while the final balloon payment represents the unpaid principal balance at maturity:
Monthly Payment (PMT) = Principal × [ r(1 + r)^A ] / [ (1 + r)^A - 1 ]
Balloon Payment Balance = Principal × [ (1 + r)^A - (1 + r)^M ] / [ (1 + r)^A - 1 ]
Where:
- Principal: Total initial loan principal borrowed.
- r (Monthly Rate): Annual Percentage Rate (APR) divided by 12 months.
- A (Amortization Period in Months): Extended term used to calculate monthly payments (e.g., 300 or 360 months).
- M (Balloon Maturity in Months): Actual duration until loan maturity when the full remaining balance is due (e.g., 60 or 120 months).
Partially Amortized Balloon Payment Benchmarks
Compare monthly payments and remaining balloon payments on a $500,000 commercial loan across varying maturity terms (25-year amortization baseline):
| Annual APR | Monthly Payment (25-Yr Basis) | Balloon Due @ Year 5 | Balloon Due @ Year 7 | Balloon Due @ Year 10 |
|---|---|---|---|---|
| 6.50% APR | $3,375.43 | $452,118.40 | $427,390.10 | $381,640.80 |
| 7.25% APR | $3,610.15 | $456,804.20 | $433,960.50 | $391,720.60 |
| 8.00% APR | $3,859.08 | $461,280.60 | $440,240.80 | $401,360.20 |
Step-by-Step Partially Amortized Loan Calculation Example
Consider a $300,000 commercial property loan structured with a 30-year amortization schedule and a 5-year balloon maturity at 7.00% APR:
- Calculate Monthly Payment: $300,000 principal amortized over 360 months at 7.00% APR = $1,995.91 per month.
- Track 5-Year Payment Total (60 Months):
60 payments × $1,995.91 = $119,754.60 total paid. - Calculate Interest Paid Over 5 Years: Interest consumed equals $100,591.20.
- Calculate Principal Reduction:
$119,754.60 - $100,591.20 = $19,163.40 principal paid. - Determine Final Balloon Payment Due @ Month 60:
$300,000 - $19,163.40 = $280,836.60 balloon payment.
Frequently Asked Questions
What is a partially amortized loan?
A partially amortized loan is a debt structure where monthly payments cover interest and a portion of principal based on a long amortization schedule, but the remaining principal balance must be paid in full as a balloon payment at maturity.
How do borrowers pay off the balloon payment at maturity?
Borrowers typically pay off balloon payments by refinancing into a new mortgage, selling the underlying real estate asset, or paying off the balance with accumulated cash reserves.
What is the difference between a fully amortized loan and a partially amortized loan?
A fully amortized loan pays off the entire principal balance over the loan term through regular monthly payments. A partially amortized loan leaves a substantial lump-sum balance (balloon payment) due at maturity.
What are the risks of a partially amortized balloon loan?
The primary risk is refinancing risk. If property values drop or credit markets tighten before maturity, the borrower may struggle to refinance or sell the property to cover the balloon payment.