Loan Comparison Calculator

Compare two loans side-by-side. See monthly payments, total cost, and interest differences to choose the best option.

This calculator runs two independent standard-amortization loans side by side and never lets one loan's inputs bleed into the other's numbers: every Loan 2 field measures exactly zero effect on Loan 1's Monthly Payment, Total Cost, and Total Interest, and vice versa (lines 13-27), so the comparison is a genuinely independent run of the same formula twice. Loan 1 Amount dominates Loan 1 Monthly Payment: its ±10% span is 20% of Monthly Payment 1 — the largest single driver, ahead of Loan 1 Interest Rate (about 14%) and Loan 1 Term (about 24% on Loan 1 Total Interest, and in the opposite direction on Monthly Payment 1: a longer term lowers the monthly payment even though it raises Total Interest 1). The bottom-line difference outputs (Payment Difference, Cost Difference, Interest Difference) are each a straight subtraction between the two loans' matching figures, and at this calculator's own defaults — identical $200,000 principal on both loans, only the rate differs (6.5% vs 7%) — that difference starts out small (about -$66/month). Because the difference is measured against that small starting gap rather than against either loan's full payment or interest total, ordinary-sized dollar swings in either loan's inputs turn into large percentage moves on the difference outputs — that reflects the size of the starting gap between the two loans, not unusual volatility in the underlying numbers. This calculator does not account for closing costs, points, or PMI on either loan — it compares principal, rate, and term only.