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New Zealand Mortgage Refinance Calculator

New Zealand fixed-rate mortgages carry a break fee if you refinance mid-term. The fee reflects the bank's cost of re-lending your balance at the lower rate for the remaining fixed period and can reach thousands of dollars. Variable (floating) rate loans carry no break fee. At the end of your fixed term, refinancing is fee-free.

Monthly saving
$331
≈ · European Central Bank rate, 2026-09-11
Break-even
10 months
Saving over term
$96,235
New rate
6.20%

Principal and interest only. Check early repayment charges before acting.

$
yr
%
%
Upfront fees affect your break-even timeline
Cumulative saving over time
When your monthly saving recovers the upfront refinancing cost

Shop during your fixed-period window

New Zealand banks typically allow you to lock in a new fixed rate up to 60 days before your current fixed period expires. This lets you secure your next rate without paying a break fee. If you wait until expiry, you have a brief window before your loan reverts to the floating rate, which is typically 1-2% higher than the best fixed rates.

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Both the current and new payments use the standard annuity formula:

M = P × [ i(1+i)^n ] / [ (1+i)^n − 1 ]

  P  outstanding balance
  n  remaining months
  i  annual rate ÷ 12
monthly saving    = current payment − new payment

break-even (months) = ceil(upfront costs ÷ monthly saving)

total saving over term = monthly saving × remaining months − upfront costs

A negative total saving means the upfront costs exceed the cumulative saving over the remaining term. Refinancing is only worthwhile if you stay in the property past the break-even point.

This page prefills 6.20% from the Reserve Bank of New Zealand — Retail interest rates on credit extended by banks B20, published 2026-06-01.

This is a reference average, not a personal offer. Your lender's rate depends on your credit score, deposit size, and loan type. The rate you are actually quoted may be meaningfully higher or lower.

The rate field is editable. Type your lender's quoted rate to see your own numbers.

Reference rate sourced from official central bank or national statistics body data where available. This is an estimate for illustrative purposes only. Confirm costs and rates with your lender before proceeding.

How the break-even is calculated

The calculator computes the monthly payment under your current loan and under the new terms. The difference is your monthly saving. Dividing the total upfront refinancing cost by that monthly saving gives the break-even in months. Before that point, the cumulative saving has not yet recovered your costs. After it, every month adds to your net saving. The chart shows exactly when that crossover happens.

What this doesn't include

The calculation is principal and interest only. It does not include any tax benefit from mortgage interest deductibility (available in some countries), the impact on your credit score of a new application, or the opportunity cost of the cash used to pay closing costs. It also does not model the risk that rates fall further after you lock in - a genuine cost of refinancing at the wrong time.

Why your lender's figures may differ

The monthly saving depends on the exact remaining balance and term, which your lender knows precisely. This calculator uses the inputs you provide. If your balance has changed since you last checked, or if your lender applies interest differently (some compute daily rather than monthly), the saving may differ slightly. Always request an exact redemption statement and a formal quote before committing to refinance.

Frequently asked questions

What is a refinance break-even period?

The break-even is the number of months it takes for your accumulated monthly savings to recover the upfront costs of refinancing. If refinancing costs £2,000 and saves you £100 a month, the break-even is 20 months. If you plan to sell or move before then, refinancing costs more than it saves.

What costs should I include in the refinancing costs field?

Include all upfront costs: arrangement or product fees, valuation fees, legal fees (if switching lenders), any early repayment charge on your current loan, and broker fees if applicable. In the US, closing costs typically run 2–5% of the loan balance. In the UK, the total is usually £1,000–3,000. Enter the full amount to see the true break-even.

Is it worth refinancing for a small rate reduction?

It depends on the break-even period relative to how long you plan to stay in the property. A 0.5% rate reduction on a £300,000 mortgage saves roughly £125 a month. If closing costs are £2,500, the break-even is 20 months - worthwhile if you are staying more than 2 years. Use the calculator above to find your specific break-even for any rate difference.

Does refinancing restart my amortisation clock?

Yes, if you refinance into a new 25-year or 30-year mortgage. This lowers monthly payments but means you pay interest for longer in total, increasing lifetime interest paid even at a lower rate. To avoid this, refinance into a term equal to your remaining years on the current loan. The break-even chart above shows total saving, not just monthly saving, so you can factor this in.

What is a no-cost refinance?

A no-cost refinance means the lender covers closing costs - but charges a slightly higher interest rate in exchange. You get immediate savings with no upfront cash, but pay a higher rate for the life of the loan. Set the refinancing costs field to zero to model this scenario and compare it against a standard refinance where you pay costs upfront.

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Written and maintained by the Reckoner team

The repayment engines behind this site are tested against worked examples published by FRED, the Bank of Canada, the Bank of England and the Reserve Bank of Australia. Found an error? Contact us

Last reviewed September 12, 2026