A household plans to spend $60,000 in its first year of retirement. Social Security and a pension will bring in $20,000, leaving $40,000 to come from savings. How large does its investment portfolio need to be?

Among common retirement withdrawal strategies, the 4% rule gives a quick starting estimate. The math works in both directions. It can show how much income a portfolio might provide or how much the household might need to save.

How the 4% Rule Works

The 4% rule uses the portfolio balance at retirement to set the first year’s withdrawal. From the second year onward, adjust the previous year’s dollar amount by the inflation rate. The goal is to maintain roughly the same purchasing power from year to year.

Where the 4% rule came from

In 1994, financial planner William Bengen tested withdrawals against historical U.S. stock and Treasury bond returns. Portfolios with 50% to 75% in stocks supported the rule’s withdrawals for at least 30 years in the historical scenarios he studied. Future retirees may experience a different mix of returns and inflation.

A two-year withdrawal example

A $1 million portfolio produces a $40,000 withdrawal in year one. If prices rise 3% during that year, the second-year withdrawal rises to $41,200. Each adjustment starts with the previous withdrawal even if the portfolio balance has fallen. Another year of 3% inflation would bring the third-year withdrawal to $42,436.

How Much Retirement Savings Does the 4% Rule Imply?

The savings estimate starts with the portion of retirement spending the portfolio must cover. Divide that first-year gap by 0.04 or multiply it by 25. For the household with a $40,000 gap, the rule implies $1 million in invested savings.

Calculate the gap your portfolio must cover

Add up essential expenses such as housing, groceries, and health care. Then add flexible expenses such as travel or entertainment. Subtract the Social Security and pension income the household expects to receive that year. Keep essentials and flexible expenses separate in the budget. If markets fall, that distinction shows which costs the household could postpone.

Separate gross withdrawals from spendable income

A $40,000 withdrawal can leave less than $40,000 for bills. For example, traditional IRA withdrawals are generally taxable while qualified Roth IRA withdrawals are tax-free. If the household needs $40,000 after taxes, it may need to withdraw more. The amount depends in part on which accounts fund the withdrawal.

When the 4% Rule Can Fall Short

A withdrawal rate that held up in past markets can produce different results under different assumptions. Morningstar estimated a 3.9% starting rate for 2026 using forecasts for returns and inflation. Its model targeted a 90% chance of funds remaining after 30 years of inflation-adjusted withdrawals.

Why early market losses matter

Sequence-of-returns risk is the risk that poor returns arrive at an especially damaging time. When losses hit early in retirement, selling investments to cover expenses leaves fewer assets to recover when markets rebound. Two retirees can earn the same average return and end up with different balances because their gains and losses arrived in a different order.

How time horizon and investment mix affect the result

Early retirees may need their savings to last well beyond 30 years. In Morningstar’s model, extending the horizon from 30 to 35 years lowered the starting rate from 3.9% to 3.5%. The mix of stocks and bonds also changes the portfolio’s growth potential and exposure to losses.

Retirement Withdrawal Strategies Beyond the 4% Rule

Suppose the household enters its second year with $800,000 after a market downturn. The 4% rule still calls for $41,200 after the inflation adjustment. Two flexible approaches respond differently to the same balance.

Withdraw a fixed percentage of the current balance

Taking 4% of $800,000 produces a $32,000 withdrawal for year two. This approach draws less from savings after a market decline. It also leaves the household with $9,200 less before taxes than the original rule would provide.

Adjust spending with guardrails

Guardrails are thresholds that trigger a change in the planned withdrawal. The scheduled $41,200 now equals 5.15% of the household’s $800,000 portfolio. If the household had set 5% as its upper threshold, it would cut the planned withdrawal. A lower threshold could trigger an increase after strong returns. Social Security and pension income can help cover essential bills while the household postpones a trip or trims other flexible spending.

Frequently Asked Questions

Can withdrawals be taken monthly?

A $40,000 annual withdrawal works out to about $3,333 per month before taxes. The rule sets an annual budget that can be divided into monthly transfers.

What happens to the withdrawal if prices fall?

Under the original approach, falling prices lower the next withdrawal. If prices fall 1%, a $40,000 withdrawal becomes $39,600 the following year.

Does the 4% rule include Social Security?

The 4% rate applies to the starting balance of the investment portfolio. Social Security helps cover household expenses and reduces what the portfolio needs to provide.

What if a required minimum distribution exceeds the planned withdrawal?

The IRS requires the distribution from the applicable retirement accounts even if the household plans to spend less. Any excess can stay in savings or go into a taxable investment account after taxes.

Conclusion

When comparing retirement withdrawal strategies, use the 4% rule to estimate how much savings a household needs to cover its spending gap. Test that estimate against a longer retirement and an early market downturn. Then identify which expenses could change if the portfolio falls or prices rise faster than expected.

These examples are for general education and do not constitute individualized financial advice.