Understand how your plan is calculated

Your FI target is the amount of FI-eligible wealth that would sustain the retirement income you want at the withdrawal rate you choose.

Inputs: desired annual retirement income; withdrawal rate (3–5%, 4% by default); and whether that income is in today’s money (the default) or a fixed amount.

How to read it: a target based on your chosen withdrawal rate, not a guaranteed safe amount or a recommendation.

Main limitation: a small change in the withdrawal rate moves the target a long way: at 3% the same income needs £1,400,000.

Only the wealth you intend to live on is measured against the target. Investments, cash and pension pots count unless you leave them out; other assets count only if you include them; property equity never does.

Main limitation: pension pots count from today, even though they can’t be drawn until pension age. A separate check on the Pensions page shows the gap your other investments need to cover.

The expected path is a deterministic forecast: one projection that applies the same return every month. It is the basis of your estimated FI date.

1. If the month’s opening value has reached the target, that month is your estimated FI date.
2. Contributions are added at the start of the month.
3. Growth applies to the opening value plus contributions, at the monthly equivalent of your annual planning return.
4. After retirement, withdrawals are taken at the end of the month.

Where the planning return comes from

By default it is derived from your holdings: an allocation-weighted average of each instrument’s historical return, using instruments with at least five years of history. It is used only when it covers at least 80% of your investments; otherwise the plan uses your own return assumption, which is 8% until you change it. You can also set your own figure at any time. The return in use is always shown beside the forecast.

How to read it: historical returns inform a planning assumption; they are not a forecast of future returns.

Main limitation: real returns vary from month to month, so the date is an estimate, not a prediction.

Contributions: one monthly amount on Free, or dated phases on Plus and Pro. They stop at retirement unless you choose otherwise.

Retirement starts when the target is reached, on a date you choose or at an age you choose.

Withdrawals follow one of three strategies: your income rising with inflation (the default), a fixed amount, or a percentage of the portfolio. In today’s-money mode the first withdrawal is your income inflated to the retirement date.

How to read it: the balance after FI shows whether the expected path still holds money after years of withdrawals at a steady return.

Main limitation: planned one-off costs, rental income and mortgage payments are recorded but not added to or taken from the forecast.

Inflation (2.5% by default) raises a today’s-money target and inflation-linked withdrawals over time. Forecast values are shown in future (nominal) money.

Each asset keeps its native currency. Current values convert into your base currency at the latest available rate, refreshed once a rate is more than 12 hours old. Recorded history keeps the rate of its day; forecasts use today’s rates.

Main limitation: future exchange-rate movements are not forecast.

Monte Carlo replays your plan many times with returns that vary from month to month, to show a range of outcomes instead of one path. It uses the same plan and FI target as the expected path.

Simulated paths

10,000, in monthly steps

Returns

Log-normal, centred on your planning return

Volatility

Fixed per asset class (equities 18%, bonds 7%, cash 1%, property 12%, other assets including pensions and crypto 16%), weighted by your FI-eligible mix

Between asset classes

No correlation is modelled; the portfolio moves as one

Fees

0.2% a year deducted from every simulated month

Inflation

Varies each month around your assumption (±1.5 points, never below −2%), slightly lower when returns are higher

Repeatability

A fixed random seed, so the same plan gives the same result

Results: the probability of reaching FI by a date you choose (your expected-path date by default); the likely FI window (the middle half of FI dates among paths that get there); and 50% and 80% bands of portfolio value over time.

How to read it: a probability is the share of simulated paths, under your assumptions. It isn’t your personal likelihood or a guarantee.

Main limitation: smooth, independent monthly returns understate extreme events.

Each simulated path continues past retirement, drawing your income, for 5, 10, 15 or 20 years (15 by default). Sustainability is the share of paths that never run out of money in that time.

Sequence-of-returns risk compares that with the paths whose portfolio fell 10% or more over the first five retired years.

Main limitation: withdrawals follow your chosen strategy every month; people usually adjust spending when markets fall.

All long-term projections are models, not predictions, and none of this is financial advice.

TaxNot modelled

Targets, returns and withdrawals are before tax.

Product and platform feesPartly

Not in the expected path; a flat 0.2% a year in Monte Carlo.

State pension and defined benefit incomeRecorded only

Shown alongside your pots but not added to either forecast.

Pension access rulesPartly

Pots count toward FI-eligible wealth from today. Access ages use the UK default minimum pension age, or an age you set. A separate check shows the gap before your pension unlocks; withdrawal order isn't modelled.

Rental income, mortgages and planned costsRecorded only

Tracked alongside the plan but not added to or deducted from the forecasts.

Country-specific regulationNot modelled

Allowances, benefits and pension rules aren't applied.

Future exchange ratesNot modelled

Forecasts convert at today's rates.

Estate planningNot modelled

Inheritance and gifting aren't considered.

Employment and life changesOnly as entered

Through the contribution phases, retirement date and scenarios you set.

Fat tails, market regimes and correlationsNot modelled

Monte Carlo uses smooth, independent monthly returns.

Questions about a calculation? Get in touch. How your data is protected is covered on the Security page.