What Is Your Retirement Number?
Your retirement number is the amount of money you need invested to fund your lifestyle without a paycheck. It is not a generic multiple of your salary. It is a specific dollar amount derived from how much you actually spend each year.
The core formula is simple:
Retirement Number = Annual Spending / Withdrawal Rate
If you spend $50,000 per year and use a 4% withdrawal rate, your retirement number is $1,250,000. If you spend $80,000 per year, your number is $2,000,000. The math is straightforward. The hard part is choosing the right withdrawal rate and accurately estimating your spending.
The 4% Rule: Where It Comes From and Whether It Still Works
The 4% rule originated from the Trinity Study, published in 1998 by three professors at Trinity University. They tested withdrawal rates from 0 to 12% across 30-year retirement periods using historical market data from 1926 to 1995. The finding: a portfolio of 50% stocks and 50% bonds survived 95% of 30-year periods when withdrawing 4% of the initial balance annually, adjusted for inflation each year.
The rule became the default retirement planning benchmark because it is simple and historically robust. But it has limitations:
Despite these limitations, 4% remains a reasonable starting point for most people. More conservative planners recommend 3.5% for early retirees or those wanting extra safety margin.
Withdrawal Rates and Survival Probabilities
The choice of withdrawal rate dramatically affects both your retirement number and the probability your portfolio survives. Here is what the research shows:
| Withdrawal Rate | 30-Year Survival (75% stocks) | 40-Year Survival (75% stocks) | Retirement Number on $50K Spending |
|---|---|---|---|
| 3.0% | ~100% | ~99% | $1,667,000 |
| 3.5% | ~99% | ~96% | $1,429,000 |
| 4.0% | ~95% | ~87% | $1,250,000 |
| 4.5% | ~83% | ~73% | $1,111,000 |
| 5.0% | ~70% | ~58% | $1,000,000 |
| 6.0% | ~50% | ~38% | $833,000 |
These figures are based on historical backtesting and are not guarantees. The drop from 4% to 5% looks small but cuts survival probability by roughly 25 percentage points over 30 years. The drop from 4% to 6% puts you at a coin flip.
For early retirees (40+ year horizon): 3.5% is the more common recommendation in the FIRE community. The extra 0.5% of conservatism adds roughly $179,000 to your target on $50,000 of spending, but meaningfully improves the odds your portfolio outlives you.
Spending: The Variable You Control Most
Most retirement calculators start with your income. That is backwards. Your retirement number is driven by your spending, not your income. Two people earning $100,000 can have wildly different retirement numbers if one spends $40,000 and the other spends $80,000.
Pre-retirement spending: Start with what you actually spend today. Track it for 3 to 6 months using our budget calculator to get an accurate baseline. Do not estimate. People consistently underestimate their spending by 10 to 20%.
Retirement spending adjustments: Some costs go down in retirement (commuting, work clothes, payroll taxes, 401(k) contributions). Others go up (healthcare before Medicare at 65, travel, hobbies). A common rule of thumb is 70 to 80% of pre-retirement spending, but this varies widely. Early retirees need to fund healthcare independently until Medicare, which can add $500 to $1,500/month depending on subsidies and plan selection.
One-time costs: Mortgage payoff, children's college, a vehicle replacement, or a major trip can create spending spikes. Build a buffer for these rather than assuming flat spending every year.
Social Security and Pensions: Reducing Your Number
If you expect Social Security or a pension, these reduce the amount you need from your portfolio. Social Security is particularly valuable because it is inflation-adjusted and guaranteed for life.
The average monthly Social Security retirement benefit in 2026 is approximately $1,976 (based on the 2025 trustee report, adjusted for the 2.5% COLA effective January 2026). For a couple where both spouses claim, combined benefits might total $3,000 to $4,000/month.
If your annual spending is $60,000 and Social Security covers $36,000 of it, your portfolio only needs to generate $24,000/year. At a 4% withdrawal rate, that drops your retirement number from $1,500,000 to $600,000.
The catch: Social Security claiming age matters enormously. Claiming at 62 reduces benefits by up to 30% compared to claiming at full retirement age (67 for most current workers). Delaying to 70 increases benefits by 24% above full retirement age. The Social Security Administration's benefit calculator provides personalized estimates.
Tax-Deferred Accounts and the Gross vs. Net Gap
If your retirement savings are primarily in tax-deferred accounts (401(k), traditional IRA), your retirement number needs to account for income tax on withdrawals. Every dollar withdrawn from a traditional 401(k) is taxed as ordinary income.
A $1,250,000 portfolio at 4% generates $50,000/year in gross withdrawals. In the 22% federal bracket with 5% state tax, you keep approximately $36,500 after taxes. If your target spending is $50,000 net, you need a larger portfolio or a mix of Roth and taxable accounts to reduce the tax drag.
Roth accounts: Withdrawals are tax-free in retirement, which means every dollar of Roth savings requires a smaller portfolio balance to produce the same net spending. A $500,000 Roth account at 4% produces $20,000/year with zero tax liability.
Taxable brokerage accounts: Long-term capital gains are taxed at preferential rates (0%, 15%, or 20% depending on income). For moderate-income retirees, the 0% capital gains bracket can cover significant investment income tax-free.
How to Reach Your Number Faster
Increase your savings rate. The most direct lever. Saving 20% of gross income instead of 10% can cut your working years roughly in half. Our compound interest calculator shows exactly how monthly contributions grow over time.
Reduce spending. Since your retirement number is based on spending, cutting annual spending by $10,000 reduces your target by $250,000 at a 4% withdrawal rate. This is a double win: you save more and need less.
Invest aggressively in your accumulation phase. A portfolio of 80 to 90% stocks has historically produced returns about 2 percentage points higher per year than a 60/40 portfolio. Over 30 years, that difference compounds into hundreds of thousands of dollars. The tradeoff is higher volatility, which matters less during accumulation than during retirement.
Capture your employer match. A 401(k) employer match is free money. A 3% match on a $75,000 salary is $2,250/year. Over 30 years at 7%, that alone grows to approximately $227,000.
Pay off your mortgage before retirement. Eliminating a $1,500/month mortgage payment reduces your required annual income by $18,000, which reduces your retirement number by $450,000 at a 4% withdrawal rate. Use our mortgage payoff early calculator to see how extra payments accelerate this.
Common Pitfalls to Avoid
Using a generic rule like 10x your salary. Rules of thumb ignore your actual spending. Someone earning $120,000 who lives on $40,000 needs far less than someone earning $80,000 who lives on $75,000. Always calculate from spending, not income.
Forgetting healthcare before Medicare. If you retire before 65, you need private health insurance or ACA marketplace coverage. Premiums can run $500 to $1,500/month depending on subsidies. This is a significant expense that many pre-retirees fail to budget for.
Assuming flat spending in retirement. Spending typically follows a U-shape: higher in early retirement (travel, activities), lower in mid-retirement, and higher again in late retirement (healthcare, long-term care). Plan for variable spending, not a flat line.
Ignoring inflation. A 4% withdrawal rate means 4% of your initial balance in year 1, then that same dollar amount adjusted for inflation each year. After 20 years at 3% inflation, your initial $50,000 withdrawal becomes approximately $90,300. Your portfolio needs to support that growth.
Not accounting for sequence-of-returns risk. If the market crashes in the first 2 to 3 years of your retirement, you are withdrawing from a depleted portfolio, which dramatically increases the chance of running out of money. This is called sequence-of-returns risk. A cash buffer of 1 to 2 years of expenses can help you avoid selling investments during a downturn.
Real-World Examples
Example: Sarah and James, both 45, targeting retirement at 58
Annual spending: $65,000. Social Security: Expected $2,400/month combined at age 67, so $28,800/year. Years until Social Security kicks in: 9 (ages 58 to 67).
Portfolio needed for ages 58 to 67 (no Social Security): $65,000 / 3.5% = $1,857,000.
Portfolio needed after age 67 (Social Security covers $28,800): ($65,000 - $28,800) / 4% = $905,000.
Their target: approximately $1,857,000 by age 58. After Social Security starts, the required balance drops significantly, so they can let the portfolio grow or spend more freely.
Current savings: $480,000 combined. Monthly contributions: $2,800. At 7% return: They reach approximately $1,850,000 in about 13 years, right at age 58.
The friction: James was laid off at 47 and was out of work for 7 months. They paused contributions and raided $12,000 from their emergency fund. The setback delayed their retirement target by roughly 9 months. They rebuilt the emergency fund first before resuming retirement contributions, which was the right call even though it cost them time.
Example: Marcus, 52, divorced, starting over with $140,000 saved
Annual spending: $42,000. Social Security: approximately $1,800/month at 67, so $21,600/year.
Portfolio needed: ($42,000 - $21,600) / 4% = $510,000 by the time Social Security starts. But he needs to cover the gap from 62 to 67 if he retires early.
Full target at 62 (no Social Security yet): $42,000 / 3.5% = $1,200,000.
Current trajectory: $140,000 at 52, contributing $1,500/month at 7% reaches approximately $560,000 by age 62. Not enough for full early retirement.
Adjusted plan: Marcus works to 65 instead of 62. At 65, his portfolio reaches approximately $720,000. Social Security at 67 covers most of his gap. He uses a part-time consulting gig from 65 to 67 to bridge the income gap without drawing down his portfolio.
The friction: Marcus's divorce settlement required him to split his 401(k), which is why he is starting over at 52 with $140,000 instead of $280,000. He also took on $15,000 in legal fees. The experience made him more disciplined about spending, and his annual costs dropped from $58,000 to $42,000, which actually lowered his retirement number significantly.
This calculator is for educational and planning purposes only. Investment returns are not guaranteed, and historical performance does not predict future results. Social Security benefit estimates are subject to change based on earnings, claiming age, and program rules. Consult a licensed financial advisor before making retirement decisions.
