The HMCalc is a modification of our Home Mortgage Calculator, designed specifically for New Zealand mortgages. The differences between this and the original spreadsheet are explained below.

The Thinking Man's Mortgage
Free Synopsis

This version of the Home Mortgage Calculator was created especially for the book The Thinking Man's Mortgage by Alan Atack. The book contains detailed information and examples about how to remove years from your mortgage. I particularly like the idea that Alan proposes for setting a series of shorter-term goals. Alan shows detailed screenshots of the HMCalc to demonstrate exactly how to implement his approach. - Jon W.

Home Mortgage Calculator for New Zealand

New Zealand Home Mortgage Calculator Screenshot

1. Download the file and save it to your computer. You'll then need to extract the spreadsheet from the .zip download.

2. Enter your loan information into the input cells - the cells with the gray borders and white background.

3. Experiment with the Extra Payment options to see how much you can save by making additional payments on the principal.

4. If the mortgage involves a floating or variable rate, use the Rate Simulation inputs to experiment with different scenarios, or enter the interest rates manually into the table (keeping in mind that by doing so, you'll be overwriting the formulas).

No Installation, No Macros - Just a simple spreadsheet

⤓ Download

License: Personal Use Only

File Type: .zip (.xls)
Size: ~350 KB
Version: 1.3

Required: Microsoft Excel® 2002(XP), 2003, or 2007

Disclaimer: The calculator is only meant to provide estimated values. We do not guarantee the results. Because your personal financial situation is unique, you should consult your financial advisor, accountant, and lending institution before making any financial decisions.

Using the Home Mortgage Calculator

Most of what you need to know about using this spreadsheet is included as comments within the cells of the worksheet. Hover your mouse of the cells with the little red triangles, and the comments will pop up to explain the particular input, result, or column.

Other than changing some of the terminology used in the calculator, the following are notable differences between the NZ version and the original:

No Tax or Insurance Info

The main difference between the New Zealand version and the original home mortgage calculator is that the tax and insurance information is removed. This actually makes the NZ version a bit cleaner and easier to use.

Variable Rates

From what I am told, mortgages are generally variable rate in New Zealand, meaning that the interest rate varies based on the market. The simulator is set up by default to simulate a rate that increases over time, but reality is that the rate will likely go up and down over time.

To track a varying interest rate, you can manually enter the interest rate for a given period within the Payment Schedule.

Payment Options

Banks in New Zealand may offer you the choice of whether to vary your payment as interest rates change or to vary the payoff period in order to keep the payment the same. This calculator is only able to handle the first case. When the interest rate changes, the payment changes.

Compound Period

The NZ version assumes that the compound period is 12 (monthly), even if you choose a Fortnightly payment frequency.