A first estimate of the money needed to retire early is annual spending divided by a withdrawal rate. A usable retirement plan goes further: it checks taxes, the years before pensions start, access to accounts and what happens when markets disappoint.
Start with spending in today’s money
Write down the life you want to fund, including housing, insurance, transport, healthcare, travel and irregular costs. Some expenses may fall after work; others may rise. Keep a paid-off mortgage separate from the ongoing costs of owning the property.
Suppose investments must provide €2,500 a month, or €30,000 a year. Ignoring withdrawal taxes for this first illustration, divide €30,000 by 0.04 to get €750,000. At 3.5%, the same calculation gives about €857,143. At 3%, it gives €1 million. These are arithmetic targets under chosen rates, not promises of sustainable income.
Understand what the 4% rule actually describes
The familiar rule starts with a withdrawal based on the initial portfolio, then adjusts that spending amount for inflation. It is different from withdrawing 4% of the current balance every year, which makes spending rise and fall with the portfolio.
A rate cannot be judged apart from the horizon, investments, spending flexibility and the test used to assess it. For example,
Morningstar’s December 2025 retirement-income research
bases its headline case on 30 years and a 90% modeled funding probability. That is a particular research setup, not a universal rule for a much longer early retirement.
Plan the bridge before pension income
A pension that begins at 67 cannot pay the bills at 50. Nor can a retirement account help before its access rules permit withdrawals. Map the years between leaving work and receiving later income, using the money actually available in each period.
For illustration, a €30,000 annual spending need and a later €12,000 net pension leave an €18,000 annual gap once that pension starts. Dividing €18,000 by 3.5% gives about €514,286 for that later phase, before any additional withdrawal tax. It does not fund the earlier years on its own. A monthly forecast connects the two phases instead of treating the pension as available from day one.
Do not confuse home equity with an income account
Use the retirement bridge calculator to test when money is actually available before pension income begins. It separates the early funding requirement from accounts that open later.
An owned home can reduce rent expenses, but its equity is not automatically withdrawable money. If the plan relies on selling, downsizing or moving, enter that event and its costs. Keep the remaining housing expenses in the plan.
Check pension statements, account access conditions and the applicable tax treatment directly. Zenarios estimates pensions and taxes with country-specific models of varying detail; those estimates do not replace the terms of your actual accounts.
How Zenarios estimates financial independence
Zenarios tests when accessible cash and investments at the chosen withdrawal rate, together with regular income available then, cover a year of spending after tax. The default rate is 3.5%. You can set a retirement spending target and change the assumptions. See the calculation methodology for the scope.
Reaching that threshold does not prove money will last throughout retirement. Compare retirement ages, inspect later shortfalls and run a market simulation. Test lower returns and a longer life. If your plan depends on cutting spending, inspect how large those cuts become.
A useful answer to “when can I retire?” therefore includes a date, the assumptions behind it and the conditions that would make you change course. Work income can also remain part of the picture: Coast FIRE and Barista FIRE describe two ways to explore that possibility.
Common questions
How do I calculate my FIRE number?
A simplified FIRE number is annual spending to be funded by investments divided by a chosen withdrawal rate. For €30,000 a year, that is €750,000 at 4% or about €857,143 at 3.5%, before withdrawal taxes. A full plan also models pension timing, accessible accounts and changing expenses.
Does reaching financial independence mean my money will never run out?
No. Zenarios' financial independence date is a threshold under the plan's assumptions. Bad return sequences, higher spending, taxes or a longer horizon can still produce a shortfall. Check stress tests and simulated futures alongside the date.
Explore Zenarios
See the Zenarios financial planning features, explore life scenarios and financial decisions, or read about how Zenarios calculates your forecast and how your financial data stays private.
Try Zenarios in your browserWritten by the maker of Zenarios, a software engineer. These guides explain planning concepts and the product; they are not a personalized financial recommendation. Illustrative calculations are not results from your plan.