The assumptions used in the NZBritannia Retirement calculator:

  • Inflation is fixed at 2% p.a. and results are shown in today's dollars. That is, all figures take into account the impact of inflation.

  • Retirement age is 65 years.

  • Life expectancy is 90 years.

  • All investments before retirement age are held in a balanced fund with an investment return of 3.5% p.a (after fees and tax).

  • All investments after retirement age are held in a conservative fund with an investment return of 2.5% p.a (after fees and tax).

  • For tax, the Prescribed Investor Rate (PIR) is assumed to be 28%.

  • If you choose to include your partner in the calculations the retirement calculator shows your income once you have both reached 65.
    The calculator assumes:

    Both under 65
    Both are saving
    One over 65, one under 65
    No drawdown, the younger person still saving
    Both over 65
    Drawing down, both not saving

    Note: This calculator is not suitable for joint calculations if there is a significant age difference between you and your partner. If that is the case, please contact one of our financial advisers to obtain a joint calculation.

  • If you choose to include NZ Super in the calculation, then you and your partner start receiving NZ Super when you each turn 65. While at least one person is under 65, any NZ Super payments received by the older person are ignored.

  • The NZ Super rate used in the calculator is after tax and is either the married rate (if with a partner) or the single rate, these amounts can be found here.

  • KiwiSaver assumptions:

    • If you are contributing to KiwiSaver, the calculator assumes contributions continue until age 65. Employer and employee contribution rates are 3% p.a before tax. Tax is calculated based on your salary and an assumed 3% employer contribution rate.

    • You and your partner (if applicable) qualify for government contributions to KiwiSaver of $521.43 per annum.

    • No first home withdrawals or one-off lump sum contributions are made.

  • Investment earnings before retirement compound annually.

  • Mortgages and any other debts are not factored into this calculation.

Calculator methodology

The retirement calculator will ask you to enter your (and, if applicable, your partner’s) current age. The retirement age is currently set at 65 because this is when NZ Super and KiwiSaver become available. You will also be asked to enter your salary as this will affect the balance of your investment in KiwiSaver (if you are contributing to KiwiSaver).

The calculator will ask you to choose a retirement goal which is a weekly dollar amount required in retirement. These figures are based on research from Massey University (NZ Retirement Expenditure Guidelines 2023), and they have been calculated to determine how much money an individual or couple will require in retirement based on the type of lifestyle they want (“no frills” – covers a basic standard of living or “choices” – covers a basic standard of living as well as some luxuries).

You will then be asked to enter your current KiwiSaver balance (and whether you are contributing to your KiwiSaver account(s)), NZBritannia investment balance (if applicable), other investments or savings, and any ongoing savings you plan to make before retiring. You are then able to enter any income streams that you may receive from work or other sources that you expect to have in retirement (that are not already included in the other information you have provided to us) and if you would like NZ Super to be included in the result.


Based on the information you have provided, the retirement calculator shows an estimate of the amount you should receive per week in retirement if the above assumptions made eventuate. You will also be shown a shortfall (or surplus) if the amount you are forecast to receive is below (or above) your retirement goal, based on what the NZ Retirement Expenditure Guidelines 2023 expect retirees to spend per week.