Inputs
Example data
Click Load to push a row into the form.
| Principal | APR | Amort yrs | Balloon m | Elapsed | Refi APR | Refi yrs | Drift | Penalty | Fees | Points | Load |
|---|---|---|---|---|---|---|---|---|---|---|---|
| $250,000 | 6.50% | 30 | 60 | 36 | 6.10% | 30 | 5 | 1.00% | $2,000 | 0.50% | |
| $500,000 | 7.25% | 25 | 84 | 18 | 6.90% | 30 | -3 | 0.00% | $3,250 | 0.25% | |
| $375,000 | 5.90% | 30 | 72 | 48 | 6.40% | 20 | 2 | 2.00% | $1,500 | 1.00% |
Results
All costs shown as present value| # | Refi date | Month index | Old payment | Balance at refi | Penalty | Fees upfront | New APR | New payment | PV old pays | PV new pays | PV total cost |
|---|
Tip: hover the chart to inspect values; the minimum point marks the most cost‑efficient month to refinance under your assumptions.
Formulas used
Monthly rate: \\( r = \\tfrac{\\text{APR}}{12} \\). Payment for principal \\(P\\) over \\(n\\) months at monthly rate \\(r\\):
\\[ \\text{PMT} = P\\,\\frac{r}{1 - (1+r)^{-n}}. \\]
Remaining balance after \\(k\\) payments:
\\[ B(k) = P(1+r)^k - \\text{PMT} \\cdot \\frac{(1+r)^k - 1}{r}. \\]
Discount factor per month: \\( d = \\tfrac{\\text{Discount APR}}{12} \\). Present value of payments \\(X_1, X_2,\\dots\\):
\\[ \\text{PV} = \\sum_{i=1}^{m} \\frac{X_i}{(1+d)^i}. \\]
Total present cost if refinancing at month \\(t\\): sum of PV of old payments until \\(t\\), plus discounted upfront items at \\(t\\) (penalty, non‑financed fees), plus PV of the new payment stream beginning after \\(t\\).
How to use this calculator
- Enter your original loan details, balloon month, and how many months have elapsed.
- Specify your evaluation discount rate, refinance terms, expected monthly rate drift, and fee structure.
- Press Calculate. We will evaluate every month from now until the balloon date.
- Review the table and the chart; the lowest total present cost marks the most cost‑efficient month to refinance.
- Export the results as CSV or PDF for records or discussion.