Loan Amortization Calculator With Balloon Payment

A loan amortization calculator with a balloon payment estimates the regular payment on an amortizing loan and the balance still due at a chosen balloon date. Enter the loan amount, APR, amortization period, and balloon date in months to see the scheduled payment, balloon balance, and total paid through that date.

Formula

The calculator treats the loan as a fixed-rate loan with equal monthly payments calculated over the full amortization period. It then computes the remaining principal after the specified number of monthly payments; that remaining balance is the estimated balloon payment.

• Monthly rate: r = APR / 1200, where APR is entered as a percentage per year.
• Number of amortization payments: n = years × 12.
• Monthly payment: A = round[P × r / (1 − (1 + r)⁻ⁿ), 2].
• Balloon balance after k payments: B = P(1 + r)^k − A[(1 + r)^k − 1] / r.

P is the original principal in dollars, A is the monthly payment in dollars, B is the estimated balloon balance in dollars, k is the number of monthly payments before the balloon is due, and r is the monthly interest rate as a decimal. The calculator requires the balloon date to fall within the amortization period. Its payment formula rounds the regular payment to cents before calculating the balance.

Worked Example

Using the calculator’s defaults: principal $20,000, APR 8%, amortization period 5 years, and balloon due after 36 months.

1. Convert the APR to a monthly rate: r = 8 / 1200 = 0.0066667.
2. Convert the amortization period to payments: n = 5 × 12 = 60.
3. Calculate and round the monthly payment: A = round[20,000 × 0.0066667 / (1 − (1.0066667)⁻⁶⁰), 2] = $405.53.
4. Calculate the balance after 36 payments: B = 20,000(1.0066667)³⁶ − 405.53[(1.0066667)³⁶ − 1] / 0.0066667 = $9,294.26.
5. Payments made by the balloon date total 36 × $405.53 = $14,599.08. Adding the balloon gives total payments of $14,599.08 + $9,294.26 = $23,893.34.

Displayed amounts are rounded to cents; formulas use the rounded monthly payment to estimate the outstanding balance. A lender may use a different rounding convention or payment schedule, so its final payoff figure can differ.

Assumptions

• The interest rate is fixed for the modeled period.
• Payments are equal monthly installments, paid at the end of each month; the balloon is due after the selected number of installments.
• Interest accrues monthly at APR divided by 12.
• Fees, taxes, insurance, mortgage insurance, escrow, late charges, and other contract-specific amounts are not included.

What a Balloon Payment Means

A balloon payment is a large final amount due at a specified point even though the regular payments have been calculated using a longer amortization schedule. Because payments in this model are spread across the full amortization period, they may not repay all principal by the balloon date. The unpaid balance becomes due then, subject to the loan contract and any accrued amounts not represented in this estimate.

Amortization period and loan term are not necessarily the same thing. The amortization period is the span used to calculate installments. The balloon date is when the modeled remaining balance is due. For example, a loan can use a 20-year amortization schedule but require its balance after five years. This calculator models that arrangement by setting the amortization period to 20 years and balloon timing to 60 months.

How to Use and Read the Results

• Enter the principal amount, not a monthly payment or the total of all scheduled payments.
• Enter the APR as a percentage: type 8 for 8%, not 0.08.
• Enter the amortization period in years and the balloon date in months. The balloon date must be at least one month and no later than the full amortization period.
• Read “Balloon balance” as the estimated outstanding principal after the regular payments up to that date. “Payments made by balloon date” is the sum of those installments; “Total paid including balloon” adds the estimated balance.

The balloon balance is not the same as total interest. It is the remaining loan balance, while interest is the cost charged over time. The total-paid result includes installment payments and the balloon principal balance, but it does not separate principal from interest or include charges excluded by the assumptions.

Limits and Common Errors

This is a simplified estimate, not a payoff quote. Actual contracts may calculate interest daily, use a different payment date convention, change the rate, or include fees and other amounts. A lender’s statement may also account for payment timing, accrued interest since the last installment, or prepayment terms, none of which this calculator can infer.

• Confusing balloon timing with amortization: A 36-month balloon date does not mean a three-year amortization period. Set each input to its own contractual duration.
• Entering a monthly rate as APR: The calculator converts annual percentage APR to a monthly rate internally; entering a monthly percentage as if annual changes the result.
• Assuming the balloon is interest-only: In this model, each regular installment includes interest and principal. The balance is calculated after those payments.
• Overlooking rounding: Payments are rounded to cents, so repeating rounded installments can leave a small difference from calculations using unrounded amounts.

If the regular payment does not cover the interest accruing for a period, the balance may grow rather than fall. The formula can represent that mathematical outcome, but it does not determine whether a particular loan contract permits it. Confirm payment structure, due dates, and the quoted amount with the lender.

Frequently Asked Questions

How do I calculate a balloon payment?
Calculate the regular installment using the loan amount, APR, and full amortization period, then apply the monthly balance formula for the number of installments before the balloon date. The resulting balance is the estimated balloon amount.

Is the balloon payment included in the monthly payment?
No. The regular monthly payment is calculated separately. The balloon is the remaining balance due at the chosen date, in addition to the installments already paid.

Can the balloon date be later than the amortization period?
Not in this calculator. The modeled balloon date must be within the amortization schedule. If a contract has another structure, use its terms and ask the lender for a payoff calculation.

Why does my lender’s balloon quote differ?
The lender may use exact payment dates, daily interest, a different rounding method, accrued interest, fees, or other contract-specific amounts. This calculator uses fixed APR divided by 12 and end-of-month payments.

Does this calculator show the total interest paid?
No. It shows the scheduled installments, estimated balloon balance, and total paid through the balloon date. Interest accounting requires separating principal reduction from each payment and may differ under the contract’s accrual method.

This result is an estimate, and the lender’s disclosure gives the exact figures.

Related

• Loan Termination Program: Meaning and Payoff Calculator
• Loan Term Sheet: Meaning, Terms, and How to Review
• Loan Term Out Calculator: Estimate Months to Payoff

in p | Loan amount | $ | 20000 | 1 | 100000000
in apr | Interest rate (APR) | % | 8 | 0.01 | 100
in yrs | Amortization period | years | 5 | 0.0833 | 50
in bm | Balloon due after | months | 36 | 1 | 600
out bal | Balloon balance | $ | p * (1 + apr / 1200) ^ bm - round(p * (apr / 1200) / (1 - (1 + apr / 1200) ^ -(yrs * 12)), 2) * ((1 + apr / 1200) ^ bm - 1) / (apr / 1200) + 0 * sqrt(yrs * 12 - bm) | 2
out pmt | Monthly payment | $ | round(p * (apr / 1200) / (1 - (1 + apr / 1200) ^ -(yrs * 12)), 2) | 2
out paid | Payments made by balloon date | $ | round(p * (apr / 1200) / (1 - (1 + apr / 1200) ^ -(yrs * 12)), 2) * bm | 2
out due | Total paid including balloon | $ | p * (1 + apr / 1200) ^ bm - round(p * (apr / 1200) / (1 - (1 + apr / 1200) ^ -(yrs * 12)), 2) * ((1 + apr / 1200) ^ bm - 1) / (apr / 1200) + round(p * (apr / 1200) / (1 - (1 + apr / 1200) ^ -(yrs * 12)), 2) * bm + 0 * sqrt(yrs * 12 - bm) | 2