Balloon Payment Estimator
Estimate the remaining debt after fixed monthly payments, with beginning or end timing, early payoff and a complete amortization table.
A QUICK WALKTHROUGH
How to use this tool
- Estimate the remaining debt after fixed monthly payments, with beginning or end timing, early payoff and a complete amortization table.
- Calculate
- Copy report / Download TXT
Formula and assumptions
i=APR/1200. End: Bₖ=Bₖ₋₁(1+i)−P. Beginning: Bₖ=(Bₖ₋₁−P)(1+i). With i=0 the unrestricted formula is L−nP. Actual payments stop at payoff: end payment=min(P,opening+interest); beginning payment=min(P,opening). Interest applies only to remaining debt. Net principal repaid=L−closing debt.
Parsed inputs and units
All amounts use one currency. Monthly rate and planned payment remain fixed; no fees, rounding to currency minor units, taxes or irregular dates. A negative unrestricted balance means an earlier payoff: this table caps the final payment, never turns debt into deposits, and shows later payments and interest as zero. Negative amortization is allowed and marked when closing debt grows. Residual debt is due after the displayed schedule. This is arithmetic, not lending or investment advice. Inputs and exports stay in this browser; 1200 rows is the display budget.
GOOD TO KNOW
Common questions
Can a balloon be negative?
The unrestricted formula may be negative after overpayment. This tool instead pays only the amount due and shows zero debt after payoff.
What is negative amortization?
Interest can exceed the payment, so the debt grows. This is supported and explicitly marked.