Rust + WebAssembly · browser-only calculation
Private loan payoff calculator
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See what your next payment really does
Next payment interest
Next payment principal
Estimated remaining interest
Estimated payoff
BREAKDOWN
Interest vs. principal over time
Acceleration zone—
80%+ of each payment goes to principal
Interest halved—
vs. first payment interest
PrincipalInterestBalance
Extra-payment impact
Payoff impact
Educational estimate, not a payoff quote or financial advice.
Uses the annual interest rate you enter and a fixed-rate monthly-payment model. It does not calculate lender-disclosed APR and excludes daily interest, fees, variable rates, penalties, taxes, insurance, and lender-specific rules. Confirm actual amounts and prepayment terms with your lender before acting.