Amortization Calculator

See required payment, total interest, total payments, payoff month, and estimated interest/time savings from recurring extra principal.

Loan principal

APR (%)

Term (years)

Extra monthly principal

Start date

Table detail

—Required payment

—Total interest

—Total payments

—Payoff months

—Extra-payment savings

Independent formula & assumption audit

Recalculate the core payment or growth path with a separate browser-local formula layer. It reads the existing inputs, does not fetch live rates, and does not replace the primary calculator.

Set the finance assumptions above, then refresh this audit.

Formula audit ready. User-entered assumptions only.

Core borrowing, saving & investing workflows

Start with the broad calculator that matches the decision, then move to a specialist only when the loan structure, cash flow, tax treatment, debt strategy or savings goal genuinely changes.

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How to use this Amortization Calculator

Enter principal, APR, term, and optional recurring extra principal. The comparison shows required payment, interest, payoff time, and the resulting schedule.