Skip to content

Mortgage Repayment Calculator

AustraliaScheduled modelClass B · rule-based estimateNo statutory rules requiredMethodology
AUD
Enter the annual rate as a percentage, like 5.99.

Repay interest only for the first years, then principal and interest.

Enter the loan amount, rate and term to see the repayment, total interest and the full schedule.

Summary

The repayment comes from the §13.5 closed form, then every period is written out as a ledger row so the interest total, the payoff date and the schedule all come from the same run.

Working

  1. §13.5 payment — the scheduled repayment solves P = B·i ÷ (1 − (1 + i)^−n) from the balance B, the periodic rate i and the remaining periods n.
  2. §13.7 recurrence — each period: interest = accruing balance × i, then closing = opening + interest + fees − payment − extra repayment.
  3. §13.9 offset — interest accrues on max(0, balance − offset × effectiveness), floored at zero; offset cash is never a principal repayment.
  4. §12.5.8 reconciliation — the ledger identity is checked on every period. A reconciliation failure invalidates the result rather than warning about it.

Assumptions

  • Interest accrues once per repayment period on the payment-period ledger. Daily accrual is not modelled at P0.
  • The first repayment falls on 1 October 2026; every date in the schedule follows from that and the repayment frequency.
  • The rate is held constant except where a dated rate-change event moves it.
  • Weekly, fortnightly and monthly frequencies use 52, 26 and 12 periods per year.

Limitations

  • Lender daily accrual, transaction timing, fee timing and rounding can differ from this model; compare the settings with your loan contract and statements.
  • Redraw availability, offset eligibility conditions, break costs and any lender fee that was not entered are not modelled.
  • Amounts beyond the entered term are not projected; a balance left unpaid at term is reported rather than extended.