The Retirement Number Formula
Your personal retirement number = (Annual Retirement Spending - Social Security Income - Other Guaranteed Income) × 25. The multiplication by 25 comes from the 4% withdrawal rule (1 divided by 0.04 = 25). For a 35-year retirement (retiring before 62), use 28.6 (1 divided by 3.5%). For a standard 30-year retirement: 25. Each year of longer retirement increases the multiplier and therefore the required portfolio.
The three inputs are the three things you must estimate accurately. Annual retirement spending is best derived from your actual current spending minus work-related costs plus anticipated retirement additions (healthcare, leisure). Social Security income comes from your ssa.gov/myaccount personalized estimate. Other guaranteed income includes pensions, rental income, part-time work, and any other predictable income source.
Personal retirement number by spending, Social Security, and other income — 4% and 3.5% withdrawal rates
| Annual Spending | SS Benefit | Other Income | Portfolio Must Fund | Number (4%) | Number (3.5%) |
|---|---|---|---|---|---|
| $45,000 | $18,000 | $0 | $27,000/yr | $675,000 | $771,000 |
| $55,000 | $22,000 | $0 | $33,000/yr | $825,000 | $943,000 |
| $65,000 | $25,000 | $0 | $40,000/yr | $1,000,000 | $1,143,000 |
| $75,000 | $28,000 | $0 | $47,000/yr | $1,175,000 | $1,343,000 |
| $90,000 | $30,000 | $15,000 (pension) | $45,000/yr | $1,125,000 | $1,286,000 |
| $110,000 | $34,000 | $0 | $76,000/yr | $1,900,000 | $2,171,000 |
Why Your Retirement Number Is Unique to You
Two people earning identical salaries can have retirement numbers that differ by $500,000 or more. Worker A plans to downsize homes (adding $150,000 to portfolio), lives frugally in retirement, has a pension covering $15,000/year, and claims Social Security at 70 for $32,000/year. Worker B plans to maintain current lifestyle, has no pension, claims Social Security at 62 for $20,000/year, and lives in a high-cost area. Same salary, dramatically different retirement numbers.
Worker A's number: $50,000 spending - $15,000 pension - $32,000 SS = $3,000 portfolio need annually. At 4%: $75,000 — essentially no portfolio needed beyond a small buffer. Worker B's number: $75,000 spending - $20,000 SS = $55,000 portfolio need annually. At 4%: $1,375,000. This variation illustrates why personalized calculation is essential rather than generic rules.
The Role of Each Income Source in Your Retirement Number
Each dollar of guaranteed annual retirement income from a non-portfolio source reduces your required portfolio by $25 (at 4% rule). A pension of $12,000/year reduces your portfolio requirement by $300,000. Social Security at $28,000/year reduces it by $700,000. Part-time work generating $15,000/year reduces it by $375,000. Understanding this equivalence helps evaluate trade-offs: is it worth delaying retirement 2 years to increase SS by $3,600/year (= $90,000 less required portfolio)? Often yes.
Each $1,000/month in guaranteed retirement income is equivalent to having $300,000 in your investment portfolio (at 4% withdrawal). Social Security of $2,000/month = $600,000 in portfolio equivalent. Social Security of $2,800/month (from delaying to 70) = $840,000 in portfolio equivalent. Optimizing Social Security is equivalent to saving an extra $240,000 in portfolio — one of the highest-return decisions in retirement planning.
Adjusting Your Number for Different Retirement Ages
The standard retirement number formula assumes a 30-year retirement (retiring at 67 to age 97). If you retire earlier or later, the number adjusts. Retiring at 55: use a 3.0-3.5% withdrawal rate (multiply by 28.6-33.3) instead of 4% — adds 14-33% to your required portfolio. Retiring at 70: a 4.5-5% withdrawal rate is reasonable for a 20-25 year retirement (multiply by 20-22) — reduces required portfolio by 12-20%.
Retirement number multiplier and portfolio requirement by retirement age for $50,000 annual portfolio-funded need
| Retirement Age | Retirement Duration | Withdrawal Rate | Multiplier | Portfolio for $50K Annual Need |
|---|---|---|---|---|
| 50 | 45 years | 3.0% | 33.3× | $1,665,000 |
| 55 | 40 years | 3.25-3.5% | 28.6-30.8× | $1,430,000-$1,540,000 |
| 60 | 35 years | 3.5-3.75% | 26.7-28.6× | $1,335,000-$1,430,000 |
| 65 | 30 years | 4.0% | 25× | $1,250,000 |
| 67 | 28 years | 4.0-4.25% | 23.5-25× | $1,175,000-$1,250,000 |
| 70 | 25 years | 4.5% | 22.2× | $1,110,000 |
How Part-Time Work Changes Your Retirement Number
Generating income from part-time work in retirement is one of the most powerful retirement number reducers available. $20,000/year in part-time income reduces your portfolio need by $500,000 at the 4% rule. For someone who can earn $30,000/year from consulting, Etsy, teaching, or freelancing for the first 5-10 years of retirement, the portfolio requirement drops dramatically — and the extended working period means more contributions and more compounding before full retirement.
The Practical Retirement Number Calculation in 4 Steps
- Build your actual retirement budget: list monthly retirement expenses by category and total them annually — do not use a percentage rule
- Get your real Social Security estimate from ssa.gov/myaccount at your planned claiming age (62, 67, or 70)
- Add any other guaranteed income: pension, rental income, planned part-time work, annuity payments
- Calculate: (Annual Spending - SS - Other Income) × 25 = your retirement number
- Add a 10-15% safety margin to the result for unexpected costs, market underperformance, and longevity risk
- If retiring before 65: use 28.6 instead of 25 (3.5% withdrawal rate) — add approximately $300,000 to typical retirement numbers
Your calculated retirement number should include a 10-15% buffer above the minimum calculation. The minimum number (at exactly 4%) has a historical success rate of 95% — meaning 5% of historical scenarios failed. A 10% buffer above the minimum increases this to near-100% historically. On a $1 million retirement number, adding a $100,000-$150,000 buffer provides meaningful additional protection against adverse market sequences.
Calculate Your Personal Retirement Number
Enter your spending goal, Social Security estimate, and other income — get your exact number and the path to reach it.
Retirement Savings and Estate Planning Considerations
Retirement accounts are the most valuable assets many Americans own — and they have unique estate planning characteristics that non-retirement assets do not share. Retirement accounts pass directly to named beneficiaries regardless of what your will says. An outdated beneficiary designation (an ex-spouse, a deceased parent, or the default 'estate') can route your life's savings to the wrong person, through probate, or create significant tax complications for heirs. Review and update beneficiary designations on every retirement account annually — it takes 15-20 minutes and is one of the highest-impact financial maintenance tasks available.
For heirs inheriting your retirement accounts, the SECURE Act 2.0 rules require most non-spouse beneficiaries to distribute inherited Traditional IRA and 401k accounts within 10 years. In their peak earning years, this forced distribution can push heirs into high tax brackets. Roth IRA conversions during your lifetime (particularly in the low-income window between early retirement and RMD age 73) convert taxable Traditional balances to Roth — giving heirs the same 10-year distribution window but without the income tax. This Roth conversion legacy planning strategy can save heirs hundreds of thousands in income taxes.
Managing Sequence of Returns Risk in Your Retirement Portfolio
Sequence of returns risk is the danger that a market decline early in retirement permanently damages your portfolio, even if average long-term returns meet your projections. The mechanism: when you withdraw from a portfolio that has just declined, you sell more shares than you would in a normal year. Those shares are no longer available to participate in the subsequent recovery, permanently reducing the portfolio's ability to sustain future withdrawals. A retiree who experiences a 30% decline in Year 1 and withdraws $48,000 is left with approximately $672,000 from a $1 million starting portfolio — and must recover from a smaller base.
The most effective defense against sequence risk is maintaining a 1-2 year cash reserve in a high-yield savings account or money market fund. This cash buffer funds living expenses during market downturns without requiring stock sales at depressed prices. The bucket strategy formalizes this defense: Bucket 1 holds 1-2 years of expenses in cash; Bucket 2 holds 3-10 years in bonds; Bucket 3 holds the long-term equity portfolio. When markets decline, withdrawals come from Bucket 1 and 2, preserving Bucket 3 for recovery. This approach has been shown in research to improve portfolio survival rates from approximately 85% to over 95% in historical simulations.
Deep Dive: How the Fidelity Retirement Benchmarks Were Calculated
The Fidelity salary-multiple benchmarks (1x at 30, 3x at 40, 6x at 50, 8x at 60, 10x at 67) emerge from a specific set of actuarial assumptions. Fidelity modeled an employee who starts working at age 25, earns a salary that grows modestly over their career, saves consistently, and retires at 67. The 15% savings rate assumption (including employer match) invested at a 5.5% annual return (reflecting Fidelity's blended equity/bond assumption) produces these salary multiple waypoints as natural compounding checkpoints along a 42-year savings career. Understanding these embedded assumptions helps you calibrate whether the benchmarks are appropriate for your specific situation.
The benchmark assumes Social Security replaces approximately 40-45% of pre-retirement income, with the savings portfolio supplementing the rest. For workers who earn above the Social Security wage base consistently, or who plan to retire before 67, these benchmarks underestimate the required savings. For workers with defined-benefit pensions providing 25%+ income replacement, the benchmarks may overstate what the investment portfolio alone needs to provide. Use the benchmarks as orientation points — if you are significantly above or below them, investigate why before making dramatic course corrections based solely on the comparison.