Home Loan Refinance Calculator with Extra Payments
This calculator helps you decide whether to refinance your home loan or continue with your existing mortgage while applying optional extra monthly or one-time payments. It reports monthly payments, total interest and fees, break-even months, and estimated payoff time when adding extra payments.
Values are estimates intended for planning and comparison only. Use the inputs to model realistic refinance fees, proposed rates, and any extra payments you may make. Results assume fixed-rate, level-payment amortization and monthly compounding unless you specify otherwise.
Compares total cost, interest, monthly payments and break-even for refinancing while accounting for extra payments and upfront refinance fees.
Inputs
Results
Current monthly payment (effective)
$1,389.58
New monthly payment (base)
$1,088.02
Net monthly savings
$301.57
Break-even (months)
10
Estimated net interest savings
$22,188.67
Total interest & fees on new loan
$144,685.69
Remaining interest on current loan
$166,874.36
Months to pay off current loan with extras
300
Total interest if you keep loan and add extras
$166,874.36
| Output | Value | Unit |
|---|---|---|
| Current monthly payment (effective) | $1,389.58 | currency |
| New monthly payment (base) | $1,088.02 | currency |
| Net monthly savings | $301.57 | currency |
| Break-even (months) | 10 | months |
| Estimated net interest savings | $22,188.67 | currency |
| Total interest & fees on new loan | $144,685.69 | currency |
| Remaining interest on current loan | $166,874.36 | currency |
| Months to pay off current loan with extras | 300 | months |
| Total interest if you keep loan and add extras | $166,874.36 | currency |
Visualization
Methodology
Calculations use standard amortization formulas to compute level monthly payments and remaining interest for fixed-rate mortgages. When an explicit current monthly payment is not provided, the tool derives it from the remaining balance, remaining term, and current rate.
Refinance comparison includes upfront refinance fees and both recurring and one-time extra payments. Break-even months are computed as refinance fees divided by net monthly savings. Payoff time with extra payments uses the closed-form solution for amortizing a loan with a fixed payment and monthly compounding.
Key takeaways
Use conservative inputs for fees and realistic extra payments when comparing scenarios.
This tool is for planning; consult your lender for exact payoffs, escrow changes, or loan-specific terms before acting.
Further resources
Expert Q&A
Does this calculator include taxes, insurance, or escrow?
No. This tool models principal and interest and allows extra payments and refinance fees. Add taxes or escrow components separately to the monthly payment inputs if you want them included in comparisons.
Are results exact?
Results are estimates based on mathematical amortization formulas. Actual payments and interest will vary with loan-specific rounding, escrow changes, or lender adjustments. See accuracy caveats in citations.
What if my current loan has prepayment penalties?
Prepayment penalties are not modelled automatically. Enter any known penalty as an additional one-time fee (e.g., in refinance fees or extra_one_time_payment) to accurately reflect costs.
How should I use the break-even result?
Break-even months estimate how long it takes for monthly savings to offset upfront refinance fees. Use it alongside your expected time in the home and total interest savings to decide whether to refinance.
Sources & citations
- NIST - Numerical Methods and Floating Point Guidance — https://www.nist.gov/
- IEEE Standard for Floating-Point Arithmetic (IEEE 754) — https://www.ieee.org/
- ISO Standards - Financial Services and Calculations — https://www.iso.org/
- OSHA - Consumer Financial Safety (guidance and safety best practices) — https://www.osha.gov/