Mortgage Comparison Calculator | Unpack Property

Compare two Australian home loan scenarios side by side - for example principal and interest versus interest-only, or a fixed rate versus a variable rate - to see total interest paid, monthly repayment difference, break-even year, and a year-by-year balance chart over the life of each loan.

What is the difference between P&I and interest-only?
Principal and Interest (P&I) means each repayment pays the bank interest AND chips away at the balance. Interest-only (IO) pays only the interest for a set period, so the balance stays the same. IO cuts early cash flow but makes the loan more expensive overall because you pay down the balance in a shorter window afterward.
How does this tool model fixed vs variable rates?
When you set a fixed period, the loan uses the fixed rate for that many years, then rolls to the variable rate for the rest of the term. The repayment is recalculated at rollover against the remaining balance over the remaining years. It does not predict rate moves - it just shows what the rollover would look like at the rates you input.
What is the breakeven point?
The month where cumulative total paid in Scenario A crosses over Scenario B. If a cheap-upfront option overtakes a cheap-overall option, that's your breakeven. It's useful for deciding: if you plan to refinance or sell before breakeven, the early-cheap option can win even if its lifetime cost is higher.
Why is total paid not the same as total interest plus the loan amount?
For interest-only loans, the principal isn't fully amortised during the IO years, so totals can look unusual. This tool shows both total interest and total paid (principal + interest). When comparing loans with different structures, total paid is the cleanest apples-to-apples number.
Does this include fees?
No. Application fees, monthly fees, offset package fees and refinance costs are not modelled. A 0.05-0.10% rate difference is often wiped out by package fees, so factor those in separately when comparing real loan products.
Is this financial advice?
No. The tool is for general information only. Actual repayments depend on your lender, loan contract, fees, rate moves, and any extra repayments or offsets. Talk to a broker or licensed adviser before refinancing or locking in a loan.
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