How are home loan interest rates calculated?

Interest rates are set by the Reserve Bank of Australia (RBA). The RBA meets on the first Tuesday of every month to announce whether the official cash rate will stay the same, increase or decrease, based on things like inflation, employment, economic growth and how much people are spending. The idea is that higher rates will slow borrowing and therefore economic activity and inflation and lower rates will do the opposite.

Lenders will then set their own home loan interest rates based on the RBA’s decision.

Types of home loan interest rates

The type of interest rate you pay on your home loan can affect how much you pay overall and each month. There are pros and cons to each type, so it’s important to take the time to find out which will suit you best. Your options include:

• Fixed rate

A fixed home loan interest rate locks in your repayment amount at a certain value and will remain the same for a set time, usually up to 5 years. This makes budgeting easier, as you’ll have a set amount that you need to pay each month that won’t be affected by rate increases. 

The downside, however, is that if rates decrease while you’re on fixed term interest, you won’t reap any of the benefits. When your fixed term ends, you have the option to either enter into a new fixed rate or switch to variable rates.
In general, fixed interest rate loans are less flexible than other types of mortgage rates, and you could end up paying penalties if you repay the loan early.

• Variable rate

A variable home loan interest rate means that your repayments might change at any time, based on changes to the cash rate or the whims of your bank. There’s less security in this type of interest rate - your repayments are subject to rises and falls in the market. 

However, it’s a popular type of home loan in Australia, as variable rates often sit lower than fixed rates. A variable interest rate might suit you if you're looking for flexibility, as you’ll have the option to make extra repayments and pay off your loan quicker.

• Comparison rate

It can be hard to compare home loan rates sometimes. Aside from the interest rate, there might be extra fees and charges built into your home loan, which means the lowest headline interest rate might not always the best option. That’s where the comparison rate comes in.

The National Credit Code requires that lenders show comparison rates - which factor in interest, fees and charges - to give you a clearer idea of the true cost of a loan. So when you compare home loan interest rates on Mozo, you’ll see an interest rate plus a comparison rate for each product.

Keep in mind that comparison rates are a guide based on a secured loan of $150,000 over 25 years, with monthly principal and interest repayments. Different values or time frames on loans will mean different comparison rates. So while the comparison rates on our site are useful for choosing the best value home loan, to find out exactly how much interest you’ll be paying you'll need to check with your lender.

How are my home loan interest repayments calculated?

How much you pay each month will depend on numerous factors, including what type of rate you’re paying, how often your interest is calculated and how long your home loan term is for. One of the important factors in determining how your interest rates are calculated is whether your home loan is an interest only or principal and interest loan. Here’s the difference:

• Interest only loans

With an interest only loan your monthly repayment consists of only the interest for the loan, and not the loan amount itself. The monthly savings can be significant if you’re not paying any of the principal loan amount, which might be a great short term solution if you’re running on a tight budget. The downside is that you won’t be making any progress toward actually owning your home.

Interest only loans are popular for investors, because they’re often counting on the value of the home increasing enough to sell the property, pay off the loan and make a profit.

Remember that you will eventually have to pay off the total loan amount, so while an interest only loan might be affordable in the short term, you should have a long term repayment plan in place.

• Principal and interest loans

With a principal and interest loan, you’re paying interest, plus a part of the total loan amount each month. At the beginning of the loan, most of your repayment will go toward paying interest and a little will go toward the loan amount. As the principal amount gets lower, so does the interest you need to pay on it, so eventually, most of your monthly repayment will be going towards the principal, while a little goes to interest.

While you’ll be paying more each month than you would with an interest only loan, the good news is that by the end of your loan term, you’ll own your home entirely.
You can use Mozo’s home loan repayments calculator to see not only how much your monthly repayments would be with either an interest only or principal and interest home loan, but also how much total interest you would pay with each one.