Interest Only vs Principal and Interest Calculator

Compare the cheaper repayment now against the payment shock and cost later.

Your details

Loan amount

Interest rate

Interest only period

yrs

Total loan term

yrs

Monthly repayment under each path

Extra interest the interest only path costs you

$44,822

Interest only repayment for the first 5 years$3,050.00
Repayment once it reverts, over the remaining 25 years$3,902.57
Repayment increase at the revert date$852.57
Repayment if you paid principal and interest from day one$3,635.97
Total interest on the interest only path$753,770

Interest only can suit an investment property where the interest is deductible, or a genuine short-term cash flow need — but the balance does not move and the repayment jump at the revert date catches people out.

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This calculator gives a general estimate only. It is not personal financial, credit or tax advice and does not take your objectives or circumstances into account.

What this calculator assumes

The same interest rate applies for the whole term; in practice interest only loans are usually priced above principal and interest.
The loan reverts to principal and interest at the end of the interest only period and is repaid over what is left of the original term.
No extra repayments, offset balance or redraw during the interest only period.
Tax treatment is not modelled — deductibility of interest on an investment loan depends on your circumstances.
Rates and thresholds current as at July 2026.

This calculator provides a general estimate only. It is not personal financial, credit or taxation advice and does not take your objectives, financial situation or needs into account. Counting Beans A.F. provides financial advice under AFSL 491754 (D&M Financial Services Pty Ltd) and credit assistance under Credit Representative number 528884. Please read our Financial Services Guide and Credit Guide, and speak with us before acting on any result.

Interest Only vs Principal and Interest Calculator

Your details

What this calculator assumes

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