Plan Your Financial Freedom
with Real Market Data
Calculate your FIRE number and model your Stocks & Shares ISA growth using 50 years of real S&P 500 and FTSE 100 returns, adjusted for actual UK inflation.
Everything You Need to Plan Your Retirement
Built on real historical data, not guesses. Every projection uses actual annual market returns.
FI Number Calculator
Calculate exactly how much you need to retire. Adjustable safe withdrawal rate, inflation-adjusted, and benchmarked against the 4% rule.
ISA Growth Calculator
Model your Stocks & Shares ISA using real S&P 500 or FTSE 100 data. Monte Carlo simulation, inflation-adjusted projections, and ISA limit tracking.
Historical Data
50 years of real S&P 500 annual returns and 41 years of FTSE 100 data, plotted against actual UK CPI inflation.
How It Works
Four steps to your retirement number
Set your annual expenses
Enter your current spending to calculate the 25× FI Number you need.
Choose your index
Pick S&P 500 or FTSE 100. We use real compounded historical returns.
Set your timeline
Drag the slider to your target retirement age. See your projected portfolio.
Run Monte Carlo
1,000 simulations using bootstrapped real data show your probability of success.
About the Data
S&P 500 returns cover 1975–2024 (50 years). FTSE 100 returns cover 1984–2024 (41 years). Both include dividends reinvested (total return). UK CPI inflation data sourced from the ONS (Office for National Statistics) covering 1975–2024. All calculations use the CAGR (Compound Annual Growth Rate) as the baseline. Monte Carlo simulations bootstrap from actual historical annual returns. Past performance is not a guarantee of future results. This tool is for educational purposes only and does not constitute regulated financial advice.