Free New Zealand money calculators
Over 100 calculators, all free, all built for New Zealand rules — our tax rates, our KiwiSaver, our mortgage market, our superannuation.
Every one is a downloadable Excel spreadsheet rather than a web form. That's deliberate. It means the calculator is yours: you keep your own copy, change the assumptions, save your numbers, and come back to it in six months when your situation has moved. Enter your details in the purple cells and the results work themselves out.
No email address required, and nothing to sign up for.
I built these because I needed them for my own finances and couldn't find New Zealand versions that did the job.
Property & mortgage
Buying, borrowing, paying it off faster, and working out whether a rental stacks up.
Mortgage calculators — repayments, extra payments, rate changes, bank offers and how much you can borrow.
How long should I fix my mortgage for? — NZ rate history since 2004, 10,000 simulations of which fixing strategy has actually worked, and the break-even rate between two terms.
Debt to income calculators — where you sit against the Reserve Bank's 6x and 7x limits, and the maximum you can borrow.
Offset mortgage calculator — what an offset facility saves you, and the rate you're really paying.
Revolving credit mortgage calculator — how much to put on it, and whether it beats fixing at a lower rate.
Mortgage break fee calculator — whether breaking your fixed term is worth what the bank charges you to get out.
Debt recycling calculators — how much of your mortgage you can turn into tax-deductible debt, and what it's worth.
How much house can I afford? — work backwards from what you could genuinely pay each year to a realistic price, plus historical affordability data for 10 regions since 2017.
Rent or buy a house — the full cost of both over the years you'd actually stay.
Saving for a house deposit — how long it'll take at your current savings rate, or what you need to put aside each month to hit a date. Both allow for house prices rising while you save.
KiwiSaver first home calculator — how long until your KiwiSaver and savings cover a deposit, when house prices are rising too.
Rental property spreadsheet — yield, cashflow and tax on a rental before you commit.
Rental property or invest elsewhere? — a rental against putting the same money into funds.
Shared home ownership (You Own) — what a shared ownership scheme actually costs over time.
Retirement & financial independence
When you could stop, how much you'd need, and what you'd actually live on.
NZ Superannuation calculator — your exact entitlement after tax, weekly through to yearly, single or as a couple.
Reverse mortgage calculator — what a reverse mortgage costs over time, and how it compares to Lifetime Home on the same income.
Retirement calculators — KiwiSaver projections, whether your savings will last (Monte Carlo), and retirement planning.
Retirement drawdown calculator — eight withdrawal strategies compared on your numbers, so you can see what each would mean for your spending and what's left.
Financial independence calculators — countdown to FI, Coast and Barista FIRE with KiwiSaver included, plus the crossover point and what your job really pays per hour.
Annuity payout calculators — what a fixed income stream would pay you, or how long your capital would last at a given payment.
Investing & net worth
What fees and tax really cost you over an investing lifetime.
Investing calculators — fees, investment tax, returns, asset allocation and currency impact. 20+ tools including IRR, rebalancing and PIE versus non-PIE.
Sharesies, Kernel and Hatch — Sharesies, Kernel and Hatch all charge a mix of percentages, flat US dollar amounts and monthly plans, which makes comparing them harder than it should be. Five calculators work out what you'd actually pay in New Zealand dollars, including which pricing plan suits you within each platform.
FIF tax calculators — whether you've crossed the $50,000 threshold, and your liability under both the FDR and CV methods.
Net worth and asset allocation — your assets broken down by category with six pie charts, showing growth versus conservative and with or without the family home, plus a net worth tracker built into the same sheet. Also compare against Stats NZ figures for your age band.
Compound interest calculator — four spreadsheets covering compounding and the rule of 72, including contributions, withdrawals and compounding frequency.
Savings calculators — goals and timeframes, plus what a purchase really costs once you count the returns you give up.
Income & tax
What actually lands in your account, and what happens to the rest.
Take home pay calculators — after tax, ACC and KiwiSaver, salary or hourly, plus secondary tax and the pre-tax salary you'd need to hit a target take-home figure.
What tax code am I on? — answer a few questions, get the right IRD code.
Student loan calculators — repayments and payoff date for New Zealand and overseas-based borrowers, including what extra payments save you.
Family Boost calculator — what you can claim back on early childhood fees.
Paid parental leave — what you'll receive, for how long, and the drop from your usual income.
Contractor rate calculator — what you'd need to charge to match your salary once leave, ACC levies, KiwiSaver and unpaid gaps are counted. Works backwards too.
Where do my tax dollars go? — your own tax bill split across what government spends it on.
GST calculator — add or strip GST at the current rate.
Everyday money
The small recurring decisions that quietly add up over a year.
Budget spreadsheet — where it all goes, on one page, including money set aside for the big irregular costs.
Debt reduction calculators — snowball or avalanche, what each costs you in interest, and how much sooner you'd be clear.
Best credit card rewards — annual fees against rewards for the way you actually spend, with the top cards ranked on cashback.
Electricity provider comparison — your usage against the plans on offer.
Buy or lease a vehicle — total cost of both over the years you'd keep it, for a personal vehicle.
Car comparison spreadsheet — running costs, not just the sticker price. Petrol, hybrid, diesel or EV, with road user charges included.
Solar panel calculator — payback period on a solar install.
Cost of petrol — what a trip or a commute really costs.
Inflation calculator — what money was worth in past years, using NZ data.
The future impact of inflation — what today's savings will buy in twenty years.
Percentage change — quick maths when you need it.
Countdown timer — a countdown to the date you're aiming at.
Big life decisions
The forks in the road where the maths is genuinely hard to eyeball.
Go to uni or straight to work? — lifetime earnings both ways, student loan included.
Stay at home parent or return to work? — childcare, tax and lost contributions, netted off against a second income.
How much life insurance do I need? — cover sized to your actual obligations, not a rule of thumb.
Life insurance or self insure? — premiums over a lifetime against building the buffer yourself.
Why these are spreadsheets
Most calculators online are web forms. You enter your numbers, get an answer, and it's gone, and if you want to change one assumption you start again.
A spreadsheet is yours. Save it, change it, keep your own version, share it with your partner or your accountant. The numbers stay where you put them.
Keeping them current
Tax rates change, KiwiSaver rules change, NZ Super rates move every year. These get updated as that happens, using figures from IRD, the Reserve Bank, ACC and Stats NZ rather than second-hand sources.
If you spot something out of date, tell me. I'd rather know.
Want help using them?
Calculators tell you what the numbers do. They can't tell you what to do about it.
If you'd like to talk any of this through with an independent, commission-free adviser, get in touch for a free 30 minute chat. No obligation.