The Formula: Multiply by 25
The most widely used rule of thumb is called the 4% Rule. It says you can safely withdraw 4% of your portfolio each year in retirement without running out of money over a 30-year period. To find your retirement number, simply flip it:
Annual Spending × 25 = Portfolio Needed
Example: $60,000/year × 25 = $1,500,000
Where does the 4% Rule come from?
The 4% Rule comes from the 1994 "Trinity Study," which analyzed 30-year retirement periods using historical stock and bond returns. A portfolio of 50–75% stocks historically survived all 30-year periods with a 4% withdrawal rate — including the Great Depression and the 1970s stagflation era. It's a guideline, not a guarantee.
Retirement Numbers by Lifestyle
These numbers represent your portfolio target — separate from Social Security income, which reduces how much you need to withdraw from savings.
| Lifestyle | Annual Spending | Retirement Number | Monthly |
|---|
| Lean — modest lifestyle, low cost-of-living area, or significant Social Security income | $40,000 | $1,000,000 | $3,333/mo |
| Comfortable — mid-range lifestyle, travel, hobbies, dining out occasionally | $70,000 | $1,750,000 | $5,833/mo |
| Affluent — comfortable travel, generous gifting, higher cost-of-living area | $120,000 | $3,000,000 | $10,000/mo |
How to Estimate Your Annual Spending
- Start with your current spending. Look at your last 12 months of bank and credit card statements. Total your actual expenses — this is your baseline.
- Subtract work-related costs. In retirement you'll save on commuting, work clothes, lunches, and payroll taxes. Subtract these from your baseline.
- Add retirement-specific costs. Healthcare tends to rise significantly in retirement. Budget for travel, hobbies, and any plans you've been deferring.
- Subtract expected Social Security. Your SS benefit reduces how much your portfolio must cover. A $2,000/month SS check = $24,000/year less you need to withdraw.
Savings Rate → Years to Retirement
Your savings rate (what % of income you save) is the single biggest lever you control. Here's how dramatically it affects your timeline, assuming 7% average annual investment growth:
| Savings Rate | Years to Retire | Retire Age (if start at 25) |
|---|
| 10% | ~46 years | 71 |
| 20% | ~37 years | 62 |
| 30% | ~28 years | 53 |
| 40% | ~22 years | 47 |
| 50% | ~17 years | 42 |
* Assumes 7% annual returns, 4% withdrawal rate, 25× target. Results are illustrative.
Limitations of the 4% Rule
- Based on 30-year retirements — retiring at 55 may require a 3%–3.5% rate instead
- Assumes a balanced stock/bond portfolio — an all-cash portfolio won't survive
- Doesn't account for unusual expenses (long-term care, large medical bills)
- Past returns don't guarantee future performance
Key Insight: If you're planning to retire before 60, or just want more confidence, use a 3.5% withdrawal rate instead of 4%. That means multiplying your annual spending by 28.6 instead of 25. The extra buffer significantly improves your odds across a 35–40 year retirement.
Key Terms
- The 4% Rule: A guideline suggesting you can withdraw 4% of your portfolio in year one of retirement, then adjust for inflation each year, with a high probability your money lasts 30 years.
- Retirement Number: The total portfolio size you need to retire comfortably. Calculated by multiplying your expected annual spending by 25 (the inverse of 4%).
- Replacement Rate: The percentage of your pre-retirement income you'll need in retirement. Most financial planners use 70%–90% as a starting estimate.
- Sequence of Returns Risk: The danger that a market downturn early in retirement — when you're withdrawing — can permanently damage your portfolio even if long-term returns are fine.
Quick Summary
- Retirement Number = Annual Spending × 25
- The 4% Rule says withdraw 4% of your portfolio per year
- Estimate spending: current expenses − work costs + healthcare + hobbies
- Social Security income reduces how much your portfolio must cover
- Savings rate is the biggest lever — going from 10% to 30% cuts timeline by 18 years
- Early retirees should use 3.5% withdrawal rate (multiply spending by 28.6)
