Rule of 25 Calculator
Slide your annual spending and your FIRE number responds instantly — 25 times your expenses, with the safe 4% withdrawal it supports. No forms, no submit button.
Include basics, housing, healthcare, travel and a buffer for the unexpected.
Or pick a lifestyle
LeanFIRE keeps spending frugal; fatFIRE funds a more luxurious retirement — and a proportionally larger portfolio.
How spending moves the target
Your FIRE target (spending × 25) across a range of annual spending levels around your current figure.
Your FIRE number
£750,00025 × your £30,000 annual spending
Safe annual withdrawal (4%)
£30,000That's per month
£2,500Withdrawing 4% of this portfolio in year one — then adjusting for inflation — has historically lasted 30+ years without running out.
Cutting spending is the most powerful lever: it shrinks the target and boosts your savings rate at the same time.
A rule of thumb, not a guarantee · how we calculate this
How this calculator works
The Rule of 25 multiplies your expected annual expenses in retirement by 25 to give a target portfolio size. It is the inverse of the 4% safe withdrawal rate: withdrawing 4% of your starting portfolio each year, adjusted for inflation, has historically lasted at least 30 years across most market conditions studied.
The rule assumes average long-term market returns and a balanced portfolio. In periods of poor performance you may need to withdraw less, and your spending will change over a long retirement — review your expense estimate regularly. Many UK investors prefer a more conservative 3–3.5% rate, which implies saving 28–33 times annual expenses.
Drawdown calculator
Stress-test withdrawals from your pot
Compound interest
See how fast you can reach the target
Pension calculator
Project your retirement savings
Disclaimer: This calculator provides estimates only and should not be considered financial advice. The calculations are based on the 4% rule, which is a general guideline and may not be suitable for all retirement scenarios. The calculator assumes a constant rate of return and does not account for market volatility, inflation, changes in spending patterns, or unexpected expenses. The 4% rule may not be appropriate for all market conditions or personal circumstances. Please consult with a qualified retirement planner for personalized advice regarding your retirement strategy.
Frequently Asked Questions
Disclaimer: These calculators provide estimates for informational purposes only and do not constitute financial advice. Calculations use 2026/27 UK tax rates and thresholds sourced from HMRC and GOV.UK. Results are illustrative and may not reflect your personal circumstances. For personalised advice, consult an FCA-authorised financial adviser.