Why This Retirement Number Could Be More Important Than Your 401(k)

Reaching $1 million in your 401(k) is a big milestone, but a seven‑figure balance can be a mirage. The question is whether all of your retirement resources—401(k), individual retirement account (IRA), brokerage account, cash, and Social Security—can be counted on to reliably replace enough of your paycheck to keep your lifestyle intact for decades.

That percentage is called your income replacement ratio, and it tells a far clearer story than any single account balance can. 

Why Million‑Dollar Balances Still Fall Short 

A 2025 survey found that Americans, on average, believe $1.3 million is the magic retirement savings number, yet nearly half expect to retire with less than $500,000. Even a full $1 million—drawn down via the classic 4% rule—produces just $40,000 a year before taxes. Factor in longer life spans, market volatility, and health care costs, and that seven-figure balance quickly loses its luster.

The reality is sobering: The average 401(k) balance of a Gen Xer is about $190,000, while the average balance for Boomers nearing or already in retirement is about $250,000. Those drawdowns at 4% would replace about $10,000 a year—a fraction of most household budgets.

Clearly, lump sums alone do not reveal whether you can sustain your lifestyle.

The Replacement Ratio You Actually Need 

Think in percentages, not dollars. Traditional financial advice recommends replacing 75% of your final after-tax salary as a reasonable starting point, while other planners cite a higher 80% to 85% rule of thumb. But replacement ratios are not one‑size‑fits‑all.

Social Security benefits are designed to replace about 40% of pre-retirement annual earnings, with lower‑income workers receiving a higher proportion and high earners receiving far less. Fidelity’s internal analysis shows that households without pensions need enough savings to replace at least 45% of their pre-retirement income, because Social Security and lower retirement taxes should fill in the rest.

The upshot: Estimate your own ratio by subtracting projected Social Security and any pension income from your target percentage. The gap that remains is the annual withdrawal your nest egg must fund.

It’s helpful to consider Kiplinger’s “rule of $1,000.” For every $1,000 of monthly income you want, you’ll need about $240,000 in savings (at a 5% withdrawal rate and 5% market return). Want $3,000 a month on top of Social Security? Plan to have saved about $720,000 in 2025 dollars—substantial, but less scary than chasing a random $1 million target.

Adjusting Your Strategy Based on Income Goals 

• Save and invest toward a ratio, not a lump sum: Use a retirement calculator that lets you plug in your desired monthly income and automatically calculates the balance required.
• Delay claiming Social Security: Each year you wait beyond full retirement age boosts benefits by about 8%, raising the guaranteed slice of your ratio.
• Shift tax buckets: Building Roth accounts means withdrawals will not raise your taxable income, lowering the gross replacement rate you need from savings.
• Consider partial annuitization: Converting a slice of your assets into a lifetime annuity can “buy” additional replacement income that you can’t outlive.
• Reexamine your spending: The Bureau of Labor Statistics notes that most retirees spend 15% to 20% less on work-related costs but more on health care. Trimming your housing costs or downsizing can tilt the ratio in your favor.

The Bottom Line 

Your crucial retirement number isn’t the balance of your 401(k). It’s the percentage of pre‑retirement pay that your total income sources will replace, after taxes.

Set a realistic goal (usually 70% to 85%), subtract expected Social Security, and you’ll know precisely how much annual cash flow your nest egg needs to generate. With that target in hand, you can adjust your savings, invest more wisely, and choose a retirement age to help ensure your post‑paycheck years are as comfortable as they are now.