How Much Do I Need to Retire?

The most common retirement number is “25 times annual expenses.” It comes from the 4% rule, which Bengen documented in 1994. The math: if a portfolio supports a 4% sustainable withdrawal rate, then 25x annual spending should fund a 30-year retirement.

The 25x rule is a useful starting point. It is also incomplete. This article walks through what it captures and what it misses.

The 25x rule, explained

Annual spending of $60,000 implies $1.5 million of retirement savings (25 × $60,000). The portfolio is assumed to be a diversified mix of stocks and bonds. The withdrawal is fixed at 4% of the starting value in year 1, adjusted annually for inflation.

The rule was derived from backtesting on historical U.S. market data. It survived the worst 30-year periods in history (1929, 1966, 1969-1973). It is approximately the highest withdrawal rate that worked in those scenarios.

What 25x misses

The rule ignores three structural factors:

1. Guaranteed income from non-portfolio sources

Most retirees have Social Security. Many have pensions. Some have annuity income. These are not “savings” — they’re separate income streams.

The relevant number is not total spending; it’s the gap between total spending and guaranteed non-portfolio income.

A retiree with $60,000 spending and $30,000 Social Security has a $30,000 portfolio-funded gap. By the 25x rule, they need $750,000 in savings — half of the headline number.

2. Essential vs discretionary spending

Essential spending (housing, healthcare, food, utilities) is non-negotiable. Discretionary spending (travel, hobbies, gifts) is. A retiree facing a portfolio drawdown can cut discretionary spending without changing their quality of life materially.

Most retirees have 65-75% essentials, 25-35% discretionary. A retiree with $60,000 total spending might have $40,000 essential and $20,000 discretionary. In a bad portfolio year, cutting $5,000 from discretionary preserves the plan; trying to cut $5,000 from essentials breaks the plan.

The 25x rule doesn’t distinguish between these. A guaranteed-income-floor strategy does.

3. Length of retirement

Bengen’s 30-year horizon was the standard assumption in 1994. A 65-year-old today has a 25% chance of living past 92. Some retirees will need 35-40 years of income.

For longer retirements, the withdrawal rate should be lower (3.0-3.5%) or the consumer needs longevity insurance via DIA / QLAC.

The income-floor approach

A more useful framework:

1. Identify essential expenses (housing, healthcare, food, utilities, basic transportation, insurance)
2. Subtract Social Security and pension from essential expenses
3. Determine annuity income needed to close the remaining essential gap
4. Size the annuity allocation based on current rates
5. Add a discretionary portfolio equal to 25x discretionary spending (or 33x for 35-year horizons)
6. Add cash reserve of 6-12 months essential expenses
7. Total = annuity allocation + portfolio + cash reserve

This produces a different (and usually lower) target number than 25x total spending.

A worked example

Consumer profile: 65 years old, $5,000/month essential ($60K/year), $2,000/month discretionary ($24K/year), Social Security $2,800/month ($33,600/year).

Step 1: Essential gap = $60,000 − $33,600 = $26,400/year ($2,200/month)

Step 2: Close gap with SPIA. At industry-average rates, $2,200/month requires ~$370,000 in premium.

Step 3: Discretionary portfolio sized at 25x: 25 × $24,000 = $600,000.

Step 4: Cash reserve at 12 months essential: $60,000.

Total retirement savings needed: $370K + $600K + $60K = $1,030,000.

Compare to 25x total spending: 25 × $84,000 = $2,100,000.

The income-floor approach produces a target roughly half the simple 25x calculation. The difference: Social Security covers most of essentials, and the SPIA handles the rest.

When 25x is approximately right

The simple 25x rule works for retirees with:

• Minimal Social Security (high-earner couples with delayed claiming reach the SS cap, but it’s still $50K-$70K/year combined — meaningful)
• No pension
• High essential spending relative to total
• 30-year horizon assumption
• Willingness to absorb sequence-of-returns risk

For most retirees, 25x is a conservative upper bound. The income-floor approach is more efficient.

The withdrawal rate question

If the consumer chooses the simple-portfolio approach (no annuity), the safe withdrawal rate has three approximate tiers:

• 4.0% withdrawal rate. 30-year retirement, balanced portfolio. Most likely to succeed historically.
• 3.5% withdrawal rate. 35-40 year retirement, balanced portfolio. Greater margin of safety.
• 3.0% withdrawal rate. Conservative for long retirements or volatile markets.

Each 0.5% reduction in withdrawal rate increases the savings target by approximately 17%. A consumer comfortable with 4% withdrawal needs $1.5M for $60K spending; at 3.5%, they need $1.71M.

The Monte Carlo question

More sophisticated retirement modeling uses Monte Carlo simulation: running 1,000+ random market scenarios to estimate the probability of running out of money.

Monte Carlo produces probability statements like “92% probability of not running out of money over 30 years at a 4% withdrawal rate.” The probability is sensitive to assumptions about expected returns and volatility, which are themselves uncertain.

For a working retirement plan, Monte Carlo is a useful sensitivity check but should not be the sole framework. Structural strategies (guaranteed income floor, cash buffer, dynamic withdrawals) reduce the dependency on probability-based assumptions.

Quick estimate

For a fast estimate of retirement readiness:

1. Annual essential spending × 25 = base savings target
2. Minus annual Social Security × 25 = adjustment for Social Security
3. Plus annual discretionary spending × 25 = discretionary portion

Example: $60,000 essential, $33,600 Social Security, $24,000 discretionary.

• Base: $60,000 × 25 = $1,500,000
• Minus Social Security: -$33,600 × 25 = -$840,000
• Plus discretionary: +$24,000 × 25 = +$600,000
• Approximate target: $1,260,000

This is a quick proxy. Real planning involves all the inputs from the income-floor approach.

For deeper coverage, see retirement paycheck strategy and the retirement income planning guide.