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Mortgage amortization schedule with extra payments
Short answer: Learn how a mortgage amortization schedule splits principal and interest and how extra payments change the remaining balance and payoff date.
An amortization schedule lists every planned payment. Each row shows the opening balance, interest for that period, principal repaid, any extra principal and the remaining balance. It is the clearest way to understand why a loan with the same monthly payment can have a very different interest cost when its term or rate changes.
For a fixed-rate repayment mortgage, interest is calculated from the balance at the start of a payment period. Early in the term, that balance is larger, so more of each scheduled payment goes to interest. As principal falls, the interest portion generally falls and the principal portion rises. The final payment is adjusted so the balance does not become negative.
Use the calculator schedule as an illustrative cash-flow model. Actual lender schedules can differ because of daily interest, payment dates, escrow, product fees, rate changes or contractual rounding.
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MortgageBreezy maintains calculation-data versions and dates in the calculator. When a stable official formula is unavailable, the tool identifies the estimate as unavailable or requires user input instead of inventing a rate.