Understanding your retirement projection
The 4% rule is a historical guideline derived from US market data; actual sustainable withdrawal rates depend on the specific sequence of market returns experienced in retirement, asset allocation, fees, and individual spending patterns.
| Withdrawal rate | Interpretation (historical context) |
|---|---|
| 3% | Very conservative; high historical probability of not depleting portfolio over 40+ years |
| 4% | Bengen (1994) 'safe' rate for a 30-year retirement with a balanced portfolio |
| 5% | Moderate risk of depletion over 30 years in adverse market sequences |
| 6%+ | Substantially elevated risk of portfolio depletion; generally not recommended for 30-year periods |
- The 4% rule is based on historical US equity and bond returns. It is a guideline, not a guarantee. Future market returns may differ from historical patterns.
- This calculator uses a simplified model: contributions are assumed to be constant and invested at the start of each month at a fixed rate of return. Real portfolios experience variable returns, fees, and changing contribution amounts.
- The model does not account for Social Security, pensions, required minimum distributions (RMDs), healthcare costs, or tax on withdrawals. These factors materially affect retirement income adequacy.
- Inflation is modeled as a single constant rate. Actual inflation varies year to year, and some retirement expenses (especially healthcare) tend to rise faster than general CPI.
What is a retirement calculator?
A retirement calculator models the accumulation phase of retirement saving: it takes a current savings balance and regular contributions, applies compound growth at an assumed rate of return over the years until the chosen retirement age, and projects the total portfolio value at retirement. This projected figure is commonly called the 'nest egg'.
The calculator then applies the 4% safe-withdrawal rule, first articulated by financial planner William Bengen in a 1994 paper in the Journal of Financial Planning, to estimate how much income the portfolio could sustain each year without being depleted over a 30-year retirement. The Trinity Study (Cooley, Hubbard and Walz, 1998) subsequently validated this guideline across historical market sequences.
The real-value result discounts the nominal nest egg by the assumed inflation rate, expressing what the accumulated amount would purchase in today's money. This helps savers gauge whether projections keep pace with rising prices over long time horizons.
How to use this retirement calculator
- Enter your current age and the age at which you plan to retire to set the accumulation period.
- Enter your current retirement savings balance and the amount you contribute each month.
- Set the expected annual investment return. Historical US equity market returns (S&P 500) have averaged roughly 10% nominally over long periods; a more conservative blended portfolio might use 5–7%.
- Set the expected annual inflation rate. The US Federal Reserve targets 2% annual inflation; longer-term historical averages are near 3%.
- Read the projected nest egg, the estimated annual and monthly income under the 4% rule, and the inflation-adjusted value in today's dollars.
The formula behind the retirement calculator
The nest egg is calculated using the future value of a lump sum plus the future value of an annuity (regular monthly contributions), both compounded at the monthly equivalent of the annual return rate. The 4% withdrawal rate is then applied to the nominal nest egg to estimate sustainable annual income. The real (inflation-adjusted) value uses the purchasing-power formula to deflate the nest egg back to present-day terms.
Часто задаваемые вопросы
What is the 4% rule in retirement planning?
The 4% rule is a guideline stating that a retiree can withdraw 4% of their portfolio in the first year of retirement, then adjust that dollar amount for inflation each subsequent year, with a high historical probability of not depleting the portfolio over a 30-year period. It was introduced by financial planner William Bengen in the Journal of Financial Planning in 1994, based on analysis of historical US stock and bond returns from 1926 onward.
How much do I need to retire?
A common rule of thumb derived from the 4% rule is to accumulate 25 times your expected annual retirement expenses (because 1/0.04 = 25). For example, if you expect to spend $50,000 per year in retirement, the target nest egg is $1,250,000. This is a planning heuristic, not a guaranteed figure, and individual circumstances vary widely.
What rate of return should I use?
Historical long-run nominal returns for US equities (S&P 500) have averaged approximately 10% per year, and for US bonds approximately 4–5%. A diversified 60/40 stock-bond portfolio has historically returned roughly 8–9% nominally. After accounting for 2–3% inflation, real returns are lower. Many financial planners use 5–7% as a conservative long-run assumption for planning purposes. These are historical references, not predictions.
What is the Trinity Study?
The Trinity Study is a 1998 paper by Philip Cooley, Carl Hubbard, and Daniel Walz, published in the AAII Journal, which analyzed historical US market data to estimate the probability of various withdrawal rates sustaining a portfolio over different time horizons. The study provided empirical support for the 4% safe-withdrawal guideline that Bengen had proposed in 1994.
Why does inflation adjustment matter for retirement planning?
Inflation erodes purchasing power over time. A nest egg of $1,000,000 projected 30 years from now at 3% annual inflation is equivalent to approximately $412,000 in today's purchasing power. Understanding the real (inflation-adjusted) value of a projected nest egg helps savers assess whether their accumulation is keeping pace with the rising cost of living.
Does this calculator account for Social Security?
No. This calculator models only the accumulation of personal savings and investment contributions. Social Security, employer pension income, annuities, and other income sources are not included. For a comprehensive retirement plan, those income streams should be estimated separately and deducted from the total annual income needed from the investment portfolio.
Источники
- Bengen WP. Determining withdrawal rates using historical data. Journal of Financial Planning 1994; 7(4): 171–180.
- Cooley PL, Hubbard CM, Walz DT. Retirement savings: choosing a withdrawal rate that is sustainable. AAII Journal 1998; 20(2): 16–21. (The 'Trinity Study'.)
- Federal Reserve Bank of St. Louis. S&P 500 historical returns and inflation data. FRED Economic Data (fred.stlouisfed.org).
- Pfau WD. An international perspective on safe withdrawal rates from retirement savings. Journal of Financial Planning 2010; 23(12): 52–61.
- Brealey RA, Myers SC, Allen F. Principles of Corporate Finance (13th ed.). McGraw-Hill, 2020. Chapter 3: Valuing Bonds.