Retirement Glide Path Calculator NZ 2026/27

Quick answer: Against a downturn in the first three years, a rising glide path lasts until year 22 while staying in growth fails in year 17. If no downturn arrives, that same protection finishes $2,084,870.51 behind. And every strategy tested still runs out after a bad start, so the withdrawal rate matters more than the allocation.

The standard advice about retirement investing is to shift steadily out of growth assets and into conservative ones as you age, and it is repeated so consistently that it rarely gets tested. This page tests it, by running four allocation strategies through identical conditions and reporting what each one produces. The results do not support a simple answer in either direction, which is itself the finding worth having. Defensive allocation genuinely helps in the one scenario that actually destroys retirements, a serious downturn in the opening years while withdrawals are already running, and the strategy that helps most is the one almost nobody recommends: starting conservative at retirement and becoming more growth-oriented over time. That works because the risk being defended against is concentrated at the beginning, so protection belongs where the danger is rather than spread evenly across thirty years. The difficulty is what the same protection costs the rest of the time. Conservative assets return less every single year whether or not a downturn ever materialises, and compounded across a long retirement the shortfall becomes very large indeed. There is also a more uncomfortable result underneath all of it. At a withdrawal rate that looks entirely reasonable, none of the four strategies survives a bad start at all. They differ only in how long the failure takes, which means the allocation debate is being conducted about the wrong variable.

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Verification & Methodology
Each year's return is the weighted blend of the growth and conservative returns at that year's allocation, using the downturn figures during downturn years and the normal figures otherwise.
Glide paths move linearly from their starting weight to their ending weight across the full period, so the year by year shape is shown rather than assumed.
Withdrawals are taken at the start of each year and the remainder earns that year's return, so money about to be spent is not credited with growth.
Withdrawals rise with inflation each year.
Every strategy faces the identical downturn, in the same years and of the same depth, so any difference in outcome comes from allocation alone.
A portfolio reaching zero is held at zero and the year recorded.
Excluded: tax, fees, rebalancing costs, NZ Superannuation, and any behavioural response such as cutting spending during a downturn.
The strategies are not exhaustive. Four shapes are compared, and many others exist, including paths that respond to market conditions rather than following a fixed schedule.
Not financial advice. Last verified: .
The portfolio
$
$
Rises with inflation each year after that.
years
Growth assets
% p.a.
% p.a.
Conservative assets
% p.a.
% p.a.
The downturn
years
% p.a.
5 years
bought by defending against a bad start
Bad start, all growth
Year 17
runs out
Bad start, rising path
Year 22
runs out
Cost if no downturn
$2,084,870.51
rising path against all growth
Strategies surviving a bad start
0 of 4
the rate is the problem

Every strategy, every scenario

StrategyNo downturnDownturn years 1 to 3Downturn years 15 to 17Downturn at the end
All growth, never change$3,000,332.78Out year 17$427,641.54$1,187,840.34
Static 60/40$1,346,627.03Out year 20$151,177.10$684,682.34
Declining glide, 80% to 20%$1,242,251.55Out year 18$233,155.98$810,217.09
Rising glide, 30% to 70%$915,462.28Out year 22Out year 30$430,015.91

Staying in growth wins three of the four scenarios outright and loses the one that matters most. No strategy wins everywhere, which is why this is a judgement rather than an optimisation.

What the protection buys and costs

StrategyYears survived after a bad startAgainst all growthFinal balance with no downturnGiven up
All growth, never change17the baseline$3,000,332.78the baseline
Static 60/40203 more$1,346,627.03$1,653,705.75
Declining glide, 80% to 20%181 more$1,242,251.55$1,758,081.23
Rising glide, 30% to 70%225 more$915,462.28$2,084,870.51

Five extra years of survival costs over two million dollars in the case where the downturn never comes. That is the trade, stated plainly.

The shape of each glide path

YearAll growthStatic 60/40Declining glideRising glide
1100.00%60.00%80.00%30.00%
5100.00%60.00%71.72%35.52%
10100.00%60.00%61.38%42.41%
15100.00%60.00%51.03%49.31%
20100.00%60.00%40.69%56.21%
25100.00%60.00%30.34%63.10%
30100.00%60.00%20.00%70.00%

Percentage held in growth assets. The two glide paths cross at about year 15, which is roughly where sequence risk stops dominating.

The first five years after a bad start

YearDeclining: growth weightDeclining: closingRising: growth weightRising: closing
180.00%$635,780.0030.00%$693,230.00
277.93%$500,778.4831.38%$594,625.23
375.86%$389,174.7732.76%$503,808.58
473.79%$377,639.8034.14%$492,823.51
571.72%$364,249.0935.52%$480,740.29

By the end of year three the rising path holds $114,633.81 more, which is the entire source of its later advantage.

The Conventional Glide Path Is The Weakest Defence

The declining path, which is what most retirement products implement, performs worst of the three defensive options against the risk it is supposed to address.

Against a downturn in years 1 to 3 it lasts until year 18, just one year longer than staying entirely in growth. A static 60/40 manages year 20 and the rising path reaches year 22.

The reason is straightforward once stated. A declining path is at its most aggressive precisely when the portfolio is largest and the sequence risk is highest, and becomes conservative only after the danger has passed.

Worked Example: Four Strategies, One Downturn

All growth: runs out in year 17 after a bad start, and finishes with $3,000,332.78 if no downturn arrives.

Static 60/40: year 20, and $1,346,627.03.

Declining glide: year 18, and $1,242,251.55.

Rising glide: year 22, and $915,462.28.

The ordering reverses completely between the two columns. Whichever strategy you prefer, you are choosing which of those columns to optimise.

The Premium Is The Problem

Protection against a downturn is paid for in every year, while the benefit only arrives if the downturn actually happens.

The rising path buys 5 additional years of survival against a bad start. If no downturn comes it finishes $2,084,870.51 behind staying in growth.

That is not an argument against it. Insurance is usually a bad deal in expectation and still worth buying when the uninsured outcome is intolerable, and running out of money at 82 is intolerable in a way that dying with less is not. But it should be recognised as insurance rather than optimisation.

The Result That Outranks All Of This

At this withdrawal rate, none of the four strategies survives a bad start. They fail in year 17, 18, 20 and 22.

No rearrangement of assets converts failure into success here. The allocation only changes how long the failure takes, and a five year delay on a thirty year retirement is not a solution.

Lowering the withdrawal rate does change the outcome, and our sequence of returns risk calculator shows where that threshold sits. Spending less is unwelcome advice and it is the only lever here that decides whether the money lasts.

What Age Has To Do With It

Moving to a conservative fund at 65 assumes the money is being spent at 65, and usually it is not.

Someone retiring at 65 may be drawing on that balance into their nineties, so a large part of it has an investment horizon measured in decades. Treating the whole balance as short-term money because of the owner's age confuses when you stop working with when each dollar gets spent.

The more useful framing is to match assets to the time until they are needed. Money for the next three years belongs in cash, and money for year twenty-five does not. Our retirement bucket strategy calculator builds that structure explicitly, and our investment time horizon risk calculator shows how the risk of a loss falls with horizon.

How To Use This

Test your own numbers before adopting any shape, because the answer moves considerably with the withdrawal rate and the gap between the two asset returns.

If every strategy fails under a bad start, that is the finding, and the allocation question can wait until the withdrawal rate is fixed. If several survive, the comparison becomes a real choice about how much expected wealth you will trade for a better worst case.

Our client portfolio projection calculator shows the range of outcomes around any single path, which is worth seeing before committing to one.

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