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Overview
Mortgage repayments typically follow an amortization schedule where each instalment includes an interest portion (charged on the current balance) and a principal portion (which reduces the balance). Early in the term, repayments are interest‑heavy; over time, the principal share grows as the balance declines. Understanding how rate, term, repayment frequency and features like offset/redraw change your total interest helps you choose a structure that fits your goals and cash‑flow. This guide explains amortization mechanics, compares P&I vs IO, shows how frequency and extra repayments shorten your loan, and links to a calculator so you can test scenarios and build a payoff plan.
Key concepts
- Principal & Interest (P&I): Standard loan where each payment reduces the balance.\
- Interest‑Only (IO): For a set period, you pay interest-only" class="glossary-link" data-glossary="interest-only">interest only; balance does not decline. Repayments jump when the loan switches to P&I.\
- Repayment frequency: Weekly/fortnightly/monthly changes the number of periods and can alter total interest slightly.\
- Rate & term: Higher rates or longer terms increase total interest materially.\
- Offset & extra repayments: Reduce effective balance and shorten the term.
Example drivers of total interest
- A 0.50% rate rise can add thousands to lifetime interest.\
- Switching from 30 to 25 years can cut interest substantially but raises repayments.
FAQs
Which repayment frequency is best?
Pick a frequency that aligns with income cycle. More frequent payments can reduce interest marginally.
IO or P&I?
IO lowers repayments initially but costs more overall. P&I steadily builds equity.
Explore your scenario with the Mortgage Repayment Calculator.
Frequently asked questions
Which repayment frequency is best?
Match your income cycle. More frequent payments can reduce total interest marginally.
What happens when IO reverts to P&I?
Repayments increase because you begin repaying principal alongside interest.
Do fees affect comparison rate?
Yes. Comparison rates include certain fees to reflect effective annual cost beyond the headline rate.
How do extra repayments help?
They reduce principal faster, lowering interest and shortening the loan term.
RealEstateCalc Editorial
Property & Finance ResearchThe RealEstateCalc editorial team researches and writes about Australian property, finance, and tax topics. All content is fact-checked against official sources including the ATO, state revenue offices, ASIC Moneysmart, and the RBA.
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