This calculator compares using your KiwiSaver for a first home deposit against leaving it invested in New Zealand, weighing the mortgage interest you would save by borrowing less against the investment growth you would give up. The first-home withdrawal is one of KiwiSaver's biggest benefits, letting you pull most of your balance out after three years of membership, leaving a thousand dollars behind, to put toward a deposit. Using it means a smaller mortgage and less interest, a guaranteed saving at your mortgage rate, but it also resets your retirement savings to a lower base and forgoes the returns that money would have earned. Which comes out ahead depends on how your mortgage rate compares with your expected investment return, and over what period. You enter the amount you would withdraw, your mortgage interest rate, the return you would expect if it stayed invested, and the number of years to compare, and the calculator shows the interest saved by using it for the deposit, the growth you would give up, and which is larger. In practice the deposit also helps you buy sooner and may avoid a low-equity premium, which this simple comparison does not capture, so treat it as one input among several. General information, not financial advice.
Ignores buying sooner and avoiding a low-equity premium, which favour using it, and the retirement impact, which favours keeping it. A first-home withdrawal leaves a $1,000 minimum. General information only.
The mortgage interest saved is the amount times your mortgage rate times the years, the interest you avoid by borrowing that much less, treated on an interest-only basis. The growth given up is the amount compounded at your expected investment return over the years, minus the starting amount. The calculator compares the two and reports which is larger.
Withdrawing 40,000 dollars to reduce a mortgage at 6.5 percent saves about 26,000 dollars of interest over 10 years. Left invested at 5 percent, the same 40,000 would grow by about 25,156 dollars. Using it for the deposit is about 844 dollars ahead, before counting buying sooner.
If you've found a bug, or would like to contact us, or learn more about James Graham and Calculate.co.nz.
Calculate.co.nz is partnered with Interest.co.nz for New Zealand's highest quality calculators and financial analysis.
All calculators and tools are provided for educational and indicative purposes only and do not constitute financial advice.
Calculate.co.nz is proudly part of the Realtor.co.nz group, New Zealand's leading property transaction literacy platform, helping Kiwis understand the home buying and selling process from start to finish. Whether you're a first home buyer navigating your first property purchase, an investor evaluating your next acquisition, or a homeowner planning to sell, Realtor.co.nz provides clear, independent, and trustworthy guidance on every step of the New Zealand property transaction journey.
Calculate.co.nz is also partnered with Health Based Building and Premium Homes to promote informed choices that lead to better long-term outcomes for Kiwi households.
Calculate.co.nz is hosted in Auckland via SiteHost new Zealand.
All content on this website, including calculators, tools, source code, and design, is protected under the Copyright Act 1994 (New Zealand). No part of this site may be reproduced, copied, distributed, stored, or used in any form without prior written permission from the owner.
© 2019 to 2026 Calculate.co.nz. All rights reserved.