Principal and Interest Calculator (Amortization)

Updated on 30 June, 2022

How much of your mortgage is going to
principal and interest?

The InfoChoice Principal and Interest Calculator makes it easy to see how much of your mortgage repayment is going towards principal and interest every month.

Just enter the loan amount, term length, interest rate and any repayments to get a complete breakdown of where your mortgage payments are going. The principal and interest rates calculator also shows you how much principal versus interest has been paid to date, so you can see how much equity you've built up.

As you can see, most of your home loan repayment goes towards interest rates in the early years of your home loan, as the principal balance is paid off over time.



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Principal and Interest Calculator FAQs

Home loan repayments, like credit card debt repayments, repay both your principal loan amount and the interest that is added onto the principal amount each month, unless you have chosen an interest-only home loan. Interest-only home loan repayments do not repay any of the principal loan amount. If you choose a principal and interest home loan, your repayments will pay down the the prinicpal loan amount each month, plus the interest, so your repayments will be higher than an interest-only mortgage.

How much of your home loan repayments are repaying the prinicpal loan amount and how much of your loan repayments are repaying the interest charged. These amounts will change over time as your home loan is repaid.

Other Calculators

Important Information to Note

The Principal and Interest Calculator provides a schedule of your monthly repayments and shows you what portion goes towards interest and what portion goes toward paying off the principal amount borrowed.

Once finished you can keep a permanent record by printing each page of the schedule. You will also be able to save the whole schedule to your computer by clicking on the save icon.

Length of Month

All months are assumed to be of equal length. In reality, many loans accrue on a daily basis leading to a varying number of days' interest dependent on the number of days in the particular month.

Number of Weeks & Fortnights in a Year

One year is assumed to contain exactly 52 weeks or 26 fortnights. This implicitly assumes that a year has 364 days rather than the actual 365 or 366.

Rounding of Amount of Each Repayment

In practice, repayments are rounded to at least the nearer cent. Note that the final repayment after the increase in repayment amount will be a partial repayment as required to reduce the loan balance to zero.

Interest rate calculator for loan repayment

Monthly repayment is calculated in respect of the rounded loan amount and using interest rate entered, not including any interest rate buffer.

The results from this Principal and Interest Calculator should be used as an indication only. Results do not represent either quotes or pre-qualifications for the product. Individual institutions apply different formulas. Information such as interest rates quoted and default figures used in the assumptions are subject to change. This principal and interest rate calculator is not intended to be relied on for the purposes of making a decision in relation to a financial product. You should consider obtaining advice from a financial services licensee before making any financial decisions.

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