Allocation by Age: The Rules of Thumb

Quick definition: Age-based allocation rules use your age as a guideline for determining how much of your portfolio to hold in stocks versus bonds, automatically reducing risk as you move toward retirement.

Key Takeaways

• The classic "100 minus your age" rule suggests holding (100 - your age) percent in stocks; a 30-year-old would hold 70% stocks and 30% bonds
• Modern variations like "110 minus your age" or "120 minus your age" account for longer lifespans and reflect that even retirees need growth exposure
• Age-based allocation naturally reduces risk as you approach retirement, when emotional tolerance for losses declines and time to recover from crashes diminishes
• These rules are heuristics, not laws; individual circumstances, risk tolerance, and financial security require adjustments around the baseline
• A glide path—systematically reducing stock allocation over decades—requires far less decision-making than timing individual allocation changes

The Classic "100 Minus Your Age" Rule

The oldest and simplest rule for age-based allocation is straightforward: subtract your age from 100, and that is the percentage you should hold in stocks. The remainder goes to bonds. A 30-year-old would hold 70% stocks and 30% bonds. A 50-year-old would hold 50% stocks and 50% bonds. A 70-year-old would hold 30% stocks and 70% bonds. A 90-year-old would hold 10% stocks and 90% bonds.

This rule emerged from historical data showing that:

1. Younger investors can afford to take risk because they have decades to recover from market crashes. A 25-year-old whose portfolio drops 30% during a bear market will likely see that portfolio recover to new highs within a few years, so the crash is merely a temporary setback.

2. Older investors have shorter time horizons and less ability to recover from losses. A 70-year-old withdrawing from their portfolio cannot wait a decade for markets to recover.

3. The risk of running out of money in retirement (longevity risk) is less pressing than the risk of losses during working years. A 30-year-old should prioritize growth to accumulate wealth. A 70-year-old should prioritize stability to preserve accumulated wealth.

The 100-minus-age rule is intuitive, easy to remember, and has guided millions of investors successfully.

Modern Variations: 110 and 120 Minus Your Age

In recent decades, life expectancy has extended significantly. A 65-year-old in 1960 had an average lifespan of about 18 more years. A 65-year-old in 2024 has an average lifespan of about 22 to 25 more years and can reasonably expect to live into their 90s. Furthermore, medical advances and healthier lifestyles have extended working years for some. A 65-year-old today might work another 5 to 10 years, and many choose to work beyond traditional retirement age.

These demographic shifts have led financial professionals to suggest more aggressive variations:

110 minus your age: A 30-year-old would hold 80% stocks and 20% bonds. A 50-year-old would hold 60% stocks and 40% bonds. A 70-year-old would hold 40% stocks and 60% bonds.

120 minus your age: A 30-year-old would hold 90% stocks and 10% bonds. A 50-year-old would hold 70% stocks and 30% bonds. A 70-year-old would hold 50% stocks and 50% bonds.

These variations recognize that even retirees and older investors benefit from stock market exposure. A 70-year-old with a 20-year lifespan will likely experience significant inflation, which stocks hedge better than bonds. Furthermore, retirees can often afford to take some risk in a portion of their portfolio if they have several years of living expenses in stable, liquid reserves.

Which variation you choose—100, 110, or 120—depends on your personal circumstances. Investors with longer family longevity, better health, continued earning capacity, or higher risk tolerance might use 110 or 120. Conservative investors or those with health concerns might use 100 or even lower.

Adjusting for Individual Circumstances

Age-based rules are guidelines, not laws. Several factors might justify deviation from the baseline:

Risk tolerance: Some people are naturally conservative and sleep poorly when their portfolio is volatile, while others are comfortable with swings. If you become panicked and sell during 30% downturns, you are taking too much risk, regardless of your age. Conversely, if you read stock market news with interest but without emotional turbulence, you might tolerate more stock exposure.

Financial security: Someone with a secure pension, substantial real estate, or family wealth can afford more stock risk than someone dependent entirely on investment returns. Similarly, someone with stable employment can take more investment risk than someone with uncertain income.

Time horizon: The classic age-based rules assume you will retire at 65 and spend your portfolio over a 20-30 year horizon. If you plan to retire at 50, you need even more conservative allocation in your 40s. If you plan to work into your 70s or beyond, you can maintain more aggressive allocation longer.

Upcoming needs: If you plan to buy a home, start a business, or make a major purchase within the next 5 years, money allocated to that goal should be in bonds or stable investments, separate from your long-term portfolio.

Life circumstances: Disability, caregiving responsibilities, health conditions, or family needs might affect how much investment risk is appropriate. These are personal factors that override generic rules.

The age-based rules provide a starting framework. Your actual allocation should be adjusted based on these personal considerations.

The Glide Path: Systematic Risk Reduction

One powerful advantage of age-based allocation rules is that they define a glide path—a systematic path of gradually reducing stock exposure over decades. Instead of making a major asset allocation decision every year, you follow a predetermined formula. For a 20-year-old on the 100-minus-age rule, the glide path looks like this:

Age	Stock %	Bond %
20	80	20
30	70	30
40	60	40
50	50	50
60	40	60
70	30	70

This glide path reduces emotional decision-making. You do not need to decide whether stocks are overvalued or undervalued, whether to increase or decrease stock exposure based on market conditions, or whether the environment is favorable for equities. You simply follow the predetermined path, rebalancing gradually as you age.

Furthermore, this systematic approach naturally forces you to buy low and sell high. As you age and reduce stock allocation, stock markets will periodically crash, making stocks cheaper. Your gradual transition from stocks to bonds means you are selling stocks at various prices—high prices, low prices, and medium prices—over decades. This dollar-cost averaging into bonds and out of stocks is far more effective than trying to time major transitions.

Stock-to-Bond Ratio Within the Framework

The allocation rules discussed so far define the total stock-to-bond ratio, but they do not specify how to split the stock allocation between US and international. A 60% stock allocation might be 40% US stocks and 20% international stocks, or 35% US stocks and 25% international stocks, or many other combinations.

For simplicity, many investors use a 70/30 or 60/40 US-to-international split within their stock allocation. A 30-year-old with 70% stocks might hold 49% US stocks (70% of 70%) and 21% international stocks (30% of 70%), with the remaining 30% in bonds.

However, some investors prefer equal weighting (50/50 US to international) or even an international-heavy tilt (40/60 US to international) if they believe international markets will outperform over the next several decades. The framework remains flexible; the key is deciding on your US-to-international split and maintaining it consistently.

Rebalancing Within an Age-Based Framework

Implementing a glide path raises a practical question: how frequently should you adjust your allocation as you age? Some investors adjust annually (or whenever they have new contributions to invest), while others adjust only every five years. The frequency matters less than the consistency. Annual adjustments are smoother and easier psychologically than jumping from 70% stocks at age 49 to 50% stocks at age 50. Five-year adjustments are practical and less administratively burdensome.

Many brokerage firms now offer target-date funds that automatically execute these glide paths. A "2055 Retirement" fund, purchased by a young investor, automatically maintains an age-appropriate allocation and gradually becomes more conservative as the fund's target date approaches. While target-date funds charge fees, they eliminate the need to manually rebalance, which appeals to some investors.

Special Cases: Early Retirees and Late Workers

The age-based rules assume traditional working years ending around age 65 and retirement lasting until age 90. For investors who deviate from this path, adjustments are necessary.

Early retirees (retiring at 50 or younger): The rules suggest very conservative allocation in early 50s (perhaps 50% stocks), but early retirees often have 40-50 year time horizons and substantial longevity risk. An early retiree might use a formula like "150 minus your age" to maintain more equity exposure, or hold a separate stock allocation and bond ladder designed to cover spending for multiple years.

Late workers (retiring at 75+): The rules suggest very low equity exposure (perhaps 25% stocks) for someone at 75, but late workers often have shorter retirement horizons (perhaps 10-15 years) and should prioritize generating income and capital preservation. They might use a traditional "100 minus age" formula or even allocate less to stocks.

The age-based rules are most applicable to the typical investor working from 25 to 65 and retiring for 25 to 30 years. For those with significantly different paths, custom adjustments are appropriate.

Linking to Implementation

Once you have determined your target allocation using age-based rules, the next step is implementing it across your three funds while considering which funds belong in which account types (401(k), IRA, taxable brokerage), explored in Account Placement: 401(k) vs IRA.

Decision flow

Next

Age-based allocation provides the framework; now we translate it into concrete allocation tables for various risk profiles in Allocation Tables by Risk Tolerance.