Financial-independence number
A financial-independence number is an estimate of the investment portfolio needed to fund a chosen annual spending gap without relying on employment income. Calculate it by dividing portfolio-funded annual spending by an assumed withdrawal rate. The result is a planning target, not a promise: changing the spending gap or the rate changes the number immediately.
Why it matters
“How much is enough?” is too vague to calculate. The financial-independence number turns it into two visible assumptions: how much annual spending the portfolio must cover, and what withdrawal rate the plan uses.
The number is not the household's total wealth. A home, emergency fund, pension rights, and inaccessible assets may belong on the balance sheet but cannot all fund portfolio withdrawals. The calculation also does not say whether a household is emotionally or practically ready to stop working. It only connects a spending gap to a portfolio target.
Calculate the number
Start with spending, then subtract reliable income that will continue without employment:
Portfolio-funded spending = annual spending - reliable non-portfolio income
Then divide that gap by the assumed withdrawal rate:
Financial-independence number = portfolio-funded annual spending / withdrawal rate
Write the rate as a decimal. A 4% rate is 0.04; a 3.5% rate is 0.035. If the assumed rate is 4%, dividing by 0.04 is the same as multiplying annual portfolio-funded spending by 25. The familiar “25 times spending” shortcut is therefore not an independent rule. It is the 4% assumption written in another form.
Worked example
A household expects annual retirement spending of €36,000. Statutory and occupational pensions are expected to cover €14,400 a year in the same inflation and tax terms. The portfolio must fund the remaining €21,600:
€36,000 - €14,400 = €21,600
| Assumed initial withdrawal rate | Calculation | Estimated portfolio target |
|---|---|---|
| 4.0% | €21,600 / 0.04 | €540,000 |
| 3.5% | €21,600 / 0.035 | ≈ €617,143 |
| 3.0% | €21,600 / 0.03 | €720,000 |
The €180,000 spread between the 4% and 3% cases is not a calculation error. It is the price of changing the withdrawal assumption. Research does not establish one universal safe rate: outcomes depend on horizon, market data, asset allocation, inflation, costs, taxes, spending flexibility, and the definition of success [1][2][3].
Avoid false precision
The formula is exact; its inputs are not. A useful estimate separates current facts from future assumptions.
| Input | Questions to test |
|---|---|
| Consumption floor | Which costs remain even if discretionary spending falls? |
| Desired spending | Does the estimate include travel, gifts, repairs, and irregular costs? |
| Pension and other income | When does each payment start, and is it stated before or after tax? |
| Withdrawal rate | What horizon, portfolio, inflation rule, fees, and success criterion support it? |
| Timing | Must the portfolio cover years before the pension starts? |
| Cross-border assets | Are currency, tax, access, and transfer restrictions reflected? |
Keep all inputs in consistent terms. Do not subtract a future nominal pension from spending measured in today's purchasing power. Do not compare after-tax spending with before-tax income. A range of scenarios is more honest than a target stated to the nearest euro.
Use the number as a scenario tool
Recalculate the target when one assumption changes. If portfolio-funded spending falls from €21,600 to €18,000, the 4% case falls from €540,000 to €450,000. If the horizon becomes longer or spending cannot flex after market losses, test a lower rate instead of assuming the 25-times shortcut still fits.
The number is most useful as a dashboard: spending, reliable income, withdrawal assumption, and resulting target. It is least useful as a status symbol or a single irreversible retirement date.
Check yourself
A household expects annual spending of €36,000 and reliable non-portfolio income of €14,400. How much annual spending must the portfolio fund, in euros?
A portfolio must fund €21,600 of annual spending. Using an assumed 4% initial withdrawal rate, what is the financial-independence number, in euros?
Why does the shortcut '25 times annual spending' produce the same target as a 4% withdrawal-rate calculation?
Which calculation keeps its inputs in consistent terms?
Sources
- William P. Bengen — Determining Withdrawal Rates Using Historical Data, Journal of Financial Planning, https://www.financialplanningassociation.org/learning/publications/journal/OCT94-determining-withdrawal-rates-using-historical-data (1994)
- Wade D. Pfau — An International Perspective on Safe Withdrawal Rates from Retirement Savings: The Demise of the 4 Percent Rule?, Journal of Financial Planning, https://papers.ssrn.com/sol3/papers.cfm?abstract_id=1699526 (2010)
- Morningstar — The State of Retirement Income: 2025, https://www.morningstar.com/content/cs-assets/v3/assets/blt9415ea4cc4157833/bltb73b87c5d0c70ead/692f43f57737a31596684522/working_file_11.19_FINAL_REVISE.pdf (2025)