Safe Withdrawal Rate

The Safe Withdrawal Rate (SWR) is the maximum percentage of a retirement portfolio that can be withdrawn annually, adjusted upward for inflation each year, while preserving the principal across a long retirement period. The most cited benchmark is the 4 per cent rule, established by financial advisor William Bengen in 1994 after analysing United States market data going back to 1926. Bengen found that a 50/50 stock-bond portfolio could safely sustain a 4 per cent inflation-adjusted withdrawal across any 30-year window in that history.

The mathematics of SWR is straightforward. If the annual withdrawal rate is 4 per cent, the corpus required to fund a given annual spend equals that spend multiplied by twenty-five. A household spending Rs 15 lakh per year therefore needs Rs 3.75 crore at retirement to support a sustainable FIRE lifestyle. Each subsequent year, the previous year's withdrawal is increased by the inflation rate, regardless of portfolio performance, which means a sequence of poor early returns can permanently impair the corpus.

The 4 per cent figure is not universal. Subsequent research has refined it under different assumptions. Wade Pfau's work using lower-yield environments suggests 3 to 3.5 per cent is safer for retirements expected to last 35-plus years or in markets with currently elevated valuations. The Trinity Study, an academic update of Bengen's work, validated the 4 per cent rate but emphasised the role of asset allocation. Dynamic withdrawal strategies, which adjust the withdrawal amount based on portfolio performance rather than mechanically increasing by inflation, can support somewhat higher initial rates.

For Indian investors, the calculation needs adjustment. Domestic equity returns have historically exceeded United States returns, which would argue for a higher rate. However, Indian CPI inflation has averaged 5-6 per cent compared to 2-3 per cent in the developed world, which reduces the real return available for withdrawal. Currency considerations, healthcare inflation that runs faster than headline CPI, and the absence of social security all argue for a more conservative rate. A reasonable Indian SWR for a 30-year retirement is typically 3.5 to 4 per cent, with the lower end appropriate for early retirees expecting a 40-50 year horizon.

SWR is a planning heuristic, not a guarantee. Three risks dominate the calculus. Sequence risk refers to the impact of poor returns in the first decade of retirement, which can be catastrophic even if the long-run average is fine. Inflation risk affects households whose spending grows faster than the official basket, particularly in healthcare and education. Longevity risk is the chance of outliving the corpus when life expectancy increases. Practical retirement planning therefore combines an SWR baseline with bucket strategies for short-term cash needs, a debt allocation that produces stable income, and equity exposure that grows the corpus across the retirement window. The Wealth Planner uses 4 per cent as the default SWR for the FIRE estimate, and this can be revised downward for those preferring a more conservative plan.