ANZ Mortgage Calculator – An Honest Review + Alternatives

LM b W

Laine Moger

Journalist and Property Educator for 6 Years

Mortgage calculators are a popular (and fun) tool for would-be home owners.

Even if you're just toying with an idea of a house purchase, it can still give you a ballpark to work with. And they might just get you a little bit excited about your future home-owning prospects.

It seems every finance website comes with its own mortgage calculator (us too). Google “mortgage calculator” and you’ll see for yourself.

But they aren’t all the same – even though it seems like they are.

ANZ’s mortgage calculator is one of the most searched calculators in Google. By our count, 14,000 people search for it every month.

But is it the best one?

In this article you’ll learn how the ANZ calculator works, and get a sense of how it compares with other calculators.

Q: How do I calculate monthly mortgage repayments?

A: The best way is to use a mortgage calculator. But, if you borrow $500,000 from the bank at 4% interest over 30 years and make a weekly repayment, you will pay the bank $550.50 per week.

Q: How long should I fix my interest rate for?

A: Right now, the 1-year fixed interest rate looks attractive.

With current interest rates there could be a real risk in people fixing for too long a term. For instance, interest rates are likely to rise, but after inflation is curbed they are likely to take a downturn.

So, if you lock in for 3 years you risk locking in a rate that looks not great today; OK in a year’s time; and expensive in 3 years’ time.

How Good Is It?

How Good Is The ANZ Calculator?

We’ve tested all the main banks’ mortgage calculators.

ANZ’s mortgage calculator is the easiest to use out of all of them – and has a good mix of function and information.

For instance, you only have to fill in 3 fields to get going and it has the ability to see what you could save in interest if you made extra repayments.

It also pulls through current interest rates (instead of you having to search for them) and shows how much you’ll pay in interest over the life of the loan.

anz calculator

However, it is a bit basic.

It’s based on a standard table mortgage and doesn’t have the ability to calculate more advanced scenarios, for example if you are splitting your mortgage across multiple interest rates, which is surprisingly common for Kiwi borrowers.

What Are The Limitations?

What Are The Limitations Of Using the ANZ Mortgage Calculator?

Now, be warned, just because you use the calculator and think: “Oh yup, I can afford a mortgage” ... doesn’t mean the bank will agree with you.

A mortgage calculator can tell you what your repayments will be depending on the size of your mortgage and the interest rate you have put in.

But it falls short of considering all the other factors the bank will look at when renewing your application, or approving a new mortgage.

For example, they will use a higher interest rate when testing if you can afford your mortgage. This is called a servicing test rate.

And they will also test your income differently, depending on how your employment is structured.

For example, ANZ will not currently take into account income earned from overtime, but Westpac will, so nurses applying for a mortgage are generally more suited to Westpac.

Similarly, BNZ currently has policies more favourable for women on maternity leave who are about to return to work.

These sort of nuances can’t possibly be factored into a calculator, and generally they are only things that a mortgage broker will readily know.


Opes Mortgage Calculator vs vs Westpac vs ASB vs BNZ – Which Mortgage Calculator Should I Use?

Sometimes subtle differences between calculators can mean that one is more user friendly than others.

So, because we went through them and had a play with each, here is our honest opinion on most of the main mortgage calculators in New Zealand.

BNZ Mortgage Calculator

This one we found to be the quickest to get started, but it has some issues you need to be aware of.

Like the ANZ calculator, this calculator is able to show you what you could save in interest if you made extra repayments and pulls through current interest rates.

And the results update automatically, which means you can instantly see the financial impact as you play around with the numbers. So we do think this one has one up on ANZ.

But again, the function is pretty basic. You can’t create a more complicated mortgage structure with different tranches or create different scenarios.

And you can’t create a more custom mortgage term; you can only set the mortgage term to 5-year increments for anything more than a 5-year term. Mortgage Calculator

The mortgage calculator has a nice design and is arguably the best looking.

On top of this you can create 3 different mortgage scenarios to compare.

However, there are a few issues with their default assumptions.

The default interest rate is set at 6%, which we argue is too high for the average user, given where current interest rates are.

The mortgage term is not capped at 30 years (the maximum term in New Zealand). This means a borrower who has never had a mortgage before might think they can extend the term out to 40 years or more to bring their mortgage repayments down.

That is unrealistic. So, it is well designed, but watch out for user error in this one.


ASB Mortgage Calculator

The ASB Mortgage calculator is the best one for serious borrowers, especially those with more complex mortgage structures.

For instance, you can split your loan into 4 segments with different interest rates and terms. Across these segments you are also able to see the average interest rates and total repayments.

We like this feature because some investors and homeowners like to split out their loans into different tranches.

However, because it can offer more complex scenarios it runs the risk of getting complicated – fast. This can be a barrier for first home buyers or investors who are just getting started.


Westpac Mortgage Calculator

Westpac’s mortgage calculator is by far the best designed, but is the least user friendly.

By this we mean you can create 2 scenarios, but you are forced to put in a deposit of at least $1.

This is a problem for some investors who may not have a deposit, and are instead looking for 100% finance for an investment property.

There are also some issues with the assumptions. Like Sorted, it doesn’t cap out the loan term at 30 years. This can lead to uninformed borrowers getting the wrong idea about what’s realistic.

It also doesn’t have a weekly repayment amount. Yes, you can do the math yourself, but some investors might prefer to have that information readily available.


Opes Partner’s Mortgage Calculator

Here’s our calculator:

As you can see, it works off 4 fields of inputs:

  • Size of mortgage
  • Interest rate
  • Mortgage term
  • Frequency of payments

This gives you an overview of what your repayments will be, how much the total interest paid will be, and how that breaks down into principal repayments.

Check out our interest-only mortgage calculator if you’re an investor wanting to jiggle some figures on what your repayments would be using an interest-only mortgage.

How does It Work?

How Does A Mortgage Calculator Work?

Most mortgage calculators work out your repayments as if it is a standard table mortgage.

This is where your entire home loan is on the same interest rate (which isn’t always the case).

It uses an amortisation table (hence why it’s called a table mortgage) to work out how much you have to repay each week, fortnight or month.

This is just a fancy way of saying “how much do I have to pay each week to completely pay off my mortgage in X years”.

And the key feature of a table mortgage is that you make the exact same payment for the length of the loan (as long as the interest rate doesn’t change).

Say you took out a $500,000 mortgage at 4% over 30 years and paid the mortgage weekly, you would pay $550.50 every single week for those 30 years.

It should be said that in actual fact your interest rate will move and your mortgage repayments will change every few years depending on how long you fix your interest rates for.

As your interest rates change, your repayments will be recalculated.

What Interest Rates Do I Use?

What Interest Rates Should I Use In The Mortgage Calculator?

Interest rates fluctuate up and down, depending on the market and the bank you choose to go with.

At the time of writing (mid-July 2022), interest rates see ANZ, BNZ, Kiwibank, ASB and Westpac’s 1-year term hover around 5.19% – 5.35%.

To see what interest rates are by the main lenders in New Zealand visit:

And if you want to see where we predict interest rates are going, see our interest rate forecast here.


Other Calculators You Can Use

As well as calculating your mortgage repayments, if you’re making a property purchase you may also like to run a couple of other numbers.

Use our capital growth calculator to see what your capital gains might be.

To see the financial picture of your investment, you can use our property investment calculator.

You may also want to see whether the property will earn you money each week, or require additional investment to keep going. Use our rental yield calculator to run these numbers.

If you want to run the numbers using another method, Opes has a full range of other calculators you can find and use.

Who are Opes Partners?
Opes Partners

What is the 3-Step Opes Coaching Programme?

1. Plan out your property investment portfolio

The first step in the programme is to co-create a plan using our MyWealth Plan software. We built this software specifically to help Kiwis create a financial plan in under an hour.

You'll leave this 1-hour session with a written down plan. Pen to paper.

2. Pick properties that fit with your plan

Once you've created your plan in step #1 – your property partner will go out and find properties that fit your plan. They'll search through projects from up to 58 developers to find the best ones for you.

When you meet again, you'll review the top picks, go through the analysis, crunch the numbers together, and then decide which ones to hold with the developer.

3. Dig into the details – Confirm it's the right property for you

Once you've selected a property, you'll work for 10 days to make sure it's the right property for you. So you'll work with your Property Partner and Client Relationship Manager to dig into the details of the property.

You'll go and look at the development and be introduced to mortgage brokers, solicitors, accountants, and property managers. Their sole job is to help you figure out if this property works for you.

And you’ll have access to all the resources, tools, and data … so when confirmation day comes, you have confidence you know you’re making the right decision.

Who is the Opes Coaching Programme the right fit for?

  • You understand the concept of property investment, but who wants help putting it into practice.
  • You want a “Done for you” property investment service, so you can be a hands-off investor.
  • You are someone who has at least a 10 year investment time horizon.
  • And finally, you’re ready to become a property investor.

Who is the Opes Coaching Programme is NOT the right fit for?

  • You’re more into the smell of paint or the colour of a wall than the numbers that stand behind an investment property.
  • You only want investments that are hands-on, so you can save a few dollars here and there.
  • You have plenty of time on your hands and want to do the property investment process yourselves.
  • You’re looking for an overnight success and want to get rich quickly.

What does it cost to work with Opes Partners and go through the programme?

It’s free. Complimentary. No Cost.


The developer pays us a marketing fee when you confirm that the property is the right fit for you. Very similar to the way a mortgage broker gets paid by the bank.

Now it's important to note that we are paid the same fixed rate no matter what property you invest in.

If it’s a $500k apartment in Christchurch or a $1.3 mil 3-bedroom townhouse in Ponsonby – we get paid the same rate.

That's important because then we can recommend the right property for you, and there's no incentive to recommend you invest in a more expensive property, just so we get paid more.

I want learn more about how Opes can help me

Learn more about the Opes Coaching Programme Here

LM b W

Laine Moger

Laine Moger has been a journalist and reporter for the last 6 years. She previously worked for Stuff, The North Shore Times and Radio NZ. She has a Bachelor of Communications (Honours) from Massey University and a Diploma of Journalism from the London School of Journalism.