Mortgage Calculator Australia
Monthly repayments, LVR, stamp duty and total interest at a glance.
Last updated: January 2025 · Built for the 2024–25 financial year
Inputs
Results
Monthly repayment
$3,694.30
Loan amount
$600,000
LVR
80%
Total interest (P&I)
$729,949
Stamp duty (NSW)
$28,957
Results are estimates only. For financial advice, consult a licensed adviser.
Overview
Full mortgage amortisation with offset & extra repayments
A mortgage is the largest financial commitment most Australians make. Understanding the amortisation schedule — how each repayment splits between interest and principal — turns a 30-year liability into a 22-year one with modest tweaks.
Adding $300/month extra to a $700,000 loan at 6.2% saves $191,000 in interest and shaves 6 years off the term. Offset accounts replicate this effect with full liquidity.
Formula
Amortised monthly payment
M = P · r(1+r)^n / ((1+r)^n − 1)
Interest_t = balance_{t-1} × r
Principal_t = M − Interest_t Mortgage levers ranked by impact
| Lever | Typical 30-yr saving on $700k |
|---|---|
| 0.5% rate cut | ≈ $80,000 |
| Pay fortnightly (½ monthly) | ≈ $90,000 + 4 yrs off |
| $300/mo extra | ≈ $191,000 + 6 yrs off |
| 100% offset $50k | ≈ $115,000 + 4 yrs off |
Pro tips
- •Always compare comparison rate, not headline rate.
- •Offset > redraw for tax flexibility on investment loans.
- •Recast (re-amortise) after lump-sum payments to lock in lower repayments.