Loan Amortization Calculator

Loan Amortization Calculator

Compute standard fixed-rate loan amortization and compare staying on your current loan versus refinancing.

Capabilities

• Monthly payment: Standard amortization payment from principal, annual rate, and term.
• Totals: Total paid over the life of the loan and total interest.
• Extra payments: When extra principal is applied each month, see effective payoff term, months saved versus the original term, and interest saved versus paying only the contractual amount.
• Compact schedule: First 12 months plus the final payment month (keeps responses small for long terms).
• Yearly rollups: Principal and interest summed by loan year, with ending balance after each year.
• Refinance comparison: Given remaining balance, current rate and months left, versus a new rate and term, see monthly payment change, total interest difference, net savings (including upfront closing costs unless rolled into principal), break-even months to recoup closing costs when the payment drops, and a concise recommendation.

Gotchas

• Rate format: Annual rates are percentages (e.g. 6.5 for 6.5%), not decimals like 0.065.
• Schedule sample: Full term is simulated internally; the returned schedule is only the first 12 months and the last month so long loans stay within a reasonable payload size.
• Zero percent: A rate of 0 is valid for an interest-free loan (payment is principal divided evenly over the term).
• Refinance totals: The comparison uses contractual totals from the standard payment formula over the stated remaining or new terms; break-even uses closing costs divided by monthly payment savings when both apply.

Test scenario

Amortization: $250,000 at 6.5% annual for 360 months with no extra payment — compare payment and total interest to a trusted calculator.

Refinance: $200,000 balance at 7% with 300 months remaining vs 5.5% on a new 360-month loan and $4,000 closing costs — review monthly savings, net savings, and break-even.