Compare total cost, not only the rate
A lower advertised interest rate does not guarantee a saving. Switching costs and a longer replacement term can increase the amount paid over the remaining life of the mortgage.
New Zealand · Home loans
Mortgage refinance calculator NZ
Compare your current mortgage with a proposed refinance after interest, loan term, break fees and switching costs.
Last reviewed: 22 August 2026
Estimated refinance difference
$90,717
modelled lifetime saving after costs
Current monthly payment
$3,533.90
Proposed monthly payment
$3,221.51
- Monthly payment difference
- $312.39
- Current remaining interest
- $560,169
- Proposed remaining interest
- $466,452
- Switching costs
- $3,000
- Payment break-even
- 10 months
A smaller repayment can still increase total cost when the proposed loan restarts over a longer term.
Planning estimate only: Ask your lender for confirmed break costs, discharge fees, cashback obligations and proposed loan terms.
How break-even is estimated
When the proposed monthly payment is lower, switching costs are divided by the monthly saving. This shows how long it could take to recover the upfront cost if both rates remain unchanged.
Why loan term matters
Restarting a mortgage over 25 or 30 years can reduce the monthly payment while allowing interest to accrue for longer. Compare the proposed term with the current remaining term.
Costs to include
Consider fixed-rate break costs, legal and valuation fees, discharge or application charges, and any previous lender cashback that must be repaid.
Refinancing a mortgage in New Zealand
New Zealand borrowers may refinance with the same lender or move to another bank or non-bank lender. Before comparing offers, request the current balance, remaining term, repayment, fixed-rate expiry and any break fee in writing. Compare effective costs after fees and incentives rather than treating cashback as a free saving.
The calculator assumes standard principal-and-interest repayments and one unchanged rate for each scenario. Split loans, revolving credit, offset accounts, interest-only periods, extra repayments and future refixing need a more detailed comparison.
New Zealand mortgage guidance
Frequently asked questions
What is the refinance break-even point?
It is the estimated number of months for a lower monthly repayment to recover the switching costs entered. If the proposed repayment is not lower, there is no payment-based break-even point.
Does a lower mortgage rate always save money?
No. Fees and a longer replacement term can outweigh the lower rate. Compare total remaining interest and costs, not only the monthly repayment.
Which refinancing costs should I include?
Include confirmed break fees, valuation, legal, discharge, application and cashback-repayment costs that apply to your scenario. Ask both lenders for current figures.
Is this mortgage approval or financial advice?
No. It is a simplified planning comparison. A lender must assess approval, servicing, property, credit and loan conditions.
Does the calculator model changing interest rates?
No. Each loan uses one unchanged rate for its entered remaining term. Actual fixed periods, floating rates and future refixing will change the outcome.