Financial Independence Calculator UK

Tax-aware projections powered by 100+ years of UK and global market history.

Built for UK financial independenceISA / SIPP / GIAHistorical backtestsInflation-adjustedFees + modern mode

Financial Independence Insights

You are on track for financial independence at age 55.

Plan sustainability: 99% across historical windows.

Projected balance at financial independence is below the minimum by £414,841.

Stable spending prioritizes predictability but is sensitive to market sequence.

Progress to 4% baseline18%

£200,000 of £1,142,857 required by the 3.5% rule.

Actual sustainability depends on your allocation and horizon.

  • Your plan remains sustainable even in historically challenging market environments.

Your plan remained sustainable in nearly all historical scenarios, demonstrating strong long-term sustainability.

Next steps to improve sustainability

  • Increase monthly savings to accelerate progress.
  • Adjust your financial independence age to allow more accumulation years.
  • Reduce annual spending to improve long-term sustainability.

You are building toward financial independence with a clear path ahead. Small adjustments can improve sustainability and timing.

Key highlights

  • Projected balance at financial independence: £728,016
  • Expected wealth at life expectancy: £1,643,857
  • State pension from age 68: £11,502
  • You could increase annual spending to £44,000 while keeping strong sustainability.
Plan sustainability
99%

86 out of 87 historical windows remained sustainable.

Plan length 60 years · Data window 18802025 (146 years)

FI Number
1,142,857£

Estimated portfolio required to sustain your £40,000 annual lifestyle target.

Baseline 3.5% rule. Sustainability reflects historical outcomes across your full horizon.

Portfolio Trajectory

This chart shows inflation-adjusted portfolio outcomes over time. The center line is the typical outcome, and the shaded range reflects better and worse historical outcomes.

P10 = lower, P50 = typical, P90 = upper. Scenarios are historical windows, not forecasts.

Single-year spikes can occur during historical rebound years.

Expected Wealth (Life Expectancy)

£1,643,857

Inflation-adjusted outcome at life expectancy

Lower-confidence scenarios

1

Historical windows with reduced sustainability

State Pension

£11,502

Annual from age 68

Range of possible outcomes

Data window: 1880–2025

Withdrawal Ordering

Simulation uses a tax-optimized sequence: ISA accounts first, followed by taxable GIA (utilizing annual allowances), and finally SIPP/Pension drawdown with a 25% tax-free lump sum.

Dataset Accuracy

Data sources vary by asset class: UK equities (JST UK), US equities (Shiller total return), global equities (JST proxy + MSCI World GBP), UK bonds (JST), global bonds (JST + IGLO/AGGG), inflation (UK CPI via JST). See Methodology and Data Sources for details.

Quick definitions

What is financial independence?

Financial independence means your invested assets can sustainably cover your spending, so work becomes optional.

What is the FI number?

The FI number is the estimated portfolio size required to fund your spending using a baseline withdrawal rate.

What is plan sustainability?

Sustainability shows how often your plan lasted the full horizon across historical periods under the selected strategy.

Sustainability can differ by strategy because some approaches trade spending stability for flexibility or intentional spend-down.

Learn more in the methodology and review the underlying data sources.

FAQ

Short answers to the most common questions.

View full FAQ

Is the 4% rule reliable in the UK?

It is a baseline rule of thumb. The backtest shows how it held up across UK and global historical periods.

Does this include UK taxes?

Yes. ISA, SIPP, and GIA withdrawals are modeled using simplified UK tax rules.

What is modern era mode?

It runs the backtest using data from 1970 onward for users who prefer recent history.

For deeper detail on assumptions, see the methodology page.

Withdrawal Strategies Explained

Stable Spending

Constant‑dollar approach. A fixed inflation‑adjusted amount is withdrawn each year, prioritizing predictable spending.

Market‑Based Spending

Percent‑of‑portfolio approach. Spending adapts to markets but can fluctuate during drawdowns.

Guardrails

Starts with stable spending and makes modest adjustments when the portfolio moves above or below expectations.

Target End‑of‑Life

Spending is calculated to gradually draw down the portfolio toward zero at life expectancy, prioritizing lifetime consumption.

Age‑Based Spending

Withdrawals adjust gradually with age using a predefined curve to reflect changing retirement needs.

Want to compare strategy mechanics? Start with the FAQ and review the methodology.