Balloon Mortgage Calculator

How a Balloon Mortgage Differs

A balloon mortgage amortizes as if over a long period (often 30 years) but actually matures in a much shorter term (5, 7, or 10 years). Monthly payments are low because they follow the 30-year schedule, but a large lump sum — the balloon — is due when the shorter term ends.

When Balloon Mortgages Make Sense

Balloon mortgages suit borrowers expecting a lump sum (property sale, bonus, inheritance) timed with the balloon date. They are risky if refinancing fails or rates spike. Commercial real estate uses them extensively; residential use has declined since 2008.

Quick example

With loan amount of 400,000 and interest rate of 7 (plus amortization period of 30 and balloon due in of 7), the result is 364,841.63. Change any figure and watch the output shift — it's often more useful to see the pattern than to memorise the formula.

Which inputs matter most

You enter Loan Amount, Interest Rate, Amortization Period, and Balloon Due In. Not every input has equal weight. Adjusting one input at a time toward extreme values shows which ones move the result most.

What's happening under the hood

Computes monthly payment as if amortized over the full amortization period, then simulates balance reduction month-by-month until the balloon year. The remaining balance at that point is the balloon payment. Results are estimates for illustration purposes only. The formula is listed in full below. If the number looks off, you can retrace the calculation by hand — that's the point of showing the working.

What the headline rate hides

Lenders quote a rate; what you pay is a blend of that rate, fees, insurance, and any early-repayment penalty built into the product. The figure here isolates the core interest cost so you can compare like-for-like across deals — then add the other costs separately before signing anything.

What this doesn't capture

The figure excludes arrangement fees, valuation costs, legal fees, insurance, and any early-repayment charges — those can add several thousand to the headline cost. Rate changes at renewal for fixed-term deals will shift the picture further. Use this for the core interest/principal math and add the other costs on top.