A Moneybren tool

FIXED or FLOATING CALCULATOR

Nobody knows where rates are going — but you have a hunch. This calculator prices your hunch: fix now, or float and ride the rate path you expect.

The loan

$
yrs
How long the loan has left to run in total.
Option 1 · Fix now
% pa
yrs
Check today’s fixed specials at your bank — these are examples.
Option 2 · Stay floating
% pa
pp/yr
Your guess: how much floating moves each year. Negative = you expect cuts.
Over the fixed period
$0
Fixed
Floating

The rate paths you’re comparing

Year-by-year detail

YearFloating rate (avg)Fixed — interestFloating — interestFixed — balanceFloating — balance
The honest bit. The floating path here is your guess — this calculator can’t predict rates and neither can your bank’s economist. What it does is make your guess pay rent: if you believe cuts are coming, this shows exactly how big and fast they’d need to be. The simple rule of thumb it confirms: floating wins only if the floating rate averages below the fixed rate over the period. Not modelled: break fees if you exit a fixed term early, the flexibility of floating (unlimited extra repayments), rate-lock offers, or splitting the loan — fixing part and floating part, which is what many borrowers actually do.

How to use this calculator

Enter your loan, then the fixed offer on the table, then today’s floating rate and how you expect it to move each year. The calculator runs both paths over the fixed period, adjusting the floating payment as its rate drifts, and totals the interest each way.

Try your optimistic guess and your pessimistic one. If fixing only loses when rates fall faster than any forecast you’ve seen, that tells you something. If floating wins even with modest cuts, that tells you something too.

This is a tool only, and none of the information it produces is financial advice. Its accuracy is not guaranteed. Always check your own figures and get advice from your own financial professionals before making decisions.

A worked example

Say you’ve got $600,000 to borrow and you’re staring at two options: fix it, or float it.

Fix, and your rate and repayment are locked – you know exactly what you’re paying for the term, no surprises. Float, and your rate can move up or down with the market, but you can throw extra repayments at it any time with no break fees.

With the OCR sitting at 2.50% in 2026 and banks tipping rates to rise, fixing locks in certainty before any climb. Floating bets on flexibility. The calculator shows you the repayment and cost of each so you’re not guessing.

What most people get wrong about fixing vs floating

People treat it like an all-or-nothing bet. It isn’t. Most Kiwis split their mortgage – fix the bulk of it for certainty, and leave a chunk floating so they can make extra repayments and stay flexible. You don’t have to pick a side.

The other mistake is chasing the lowest rate on the board without thinking about what you actually need. Floating usually carries a higher rate, but if you’re about to get a bonus or sell something and want to smash the loan down, that flexibility can be worth more than a slightly lower fixed rate.

And nobody can reliably time rates – not you, not the bank, not the economists who get paid to guess. So the real question isn’t “where are rates going?” It’s “how much certainty do I want, and how much flexibility do I need?” Answer that, and the split sorts itself out.

This calculator and page are general information only and not financial advice. Everyone’s circumstances will vary – always do your own research and consult your own financial professionals before making decisions.