Ask people how much they need to retire, and there is a good chance they can throw out a number almost instantly. Maybe it is $1 million because that is what they have always heard, or $2 million because some calculator somewhere told them that is a good number.
You could also say $3 million, because it sounds safer than $2 million. But in a real sense, none of it matters. All of these figures sound concrete, and that is precisely what makes them dangerous. Most retirement numbers rest on an assumption so flawed it can quietly invalidate the entire calculation.
Those two words are “spending rate.” Not investment returns, not portfolio size. The number you actually need in retirement is almost entirely determined by what you plan to spend. Most people either significantly underestimate that figure or borrow it from a generic formula that has nothing to do with their real lives.
Where the Standard Formula Breaks Down
The 4% rule is the most widely cited framework in retirement planning. Financial planner Bill Bengen developed it in 1994 after analyzing U.S. market data going back to 1926. The rule holds that withdrawing 4% of your portfolio annually gives the money a reasonable chance of lasting 30 years. So $1 million supports roughly $40,000 a year in withdrawals, $2 million supports $80,000, and so on.
The rule has been updated and debated many times since. Morningstar’s December 2025 research set 3.9% as the safe starting withdrawal rate for retirees in 2026, up from 3.7% the prior year, based on forward-looking return and inflation projections targeting a 90% success rate over 30 years with a balanced portfolio. For retirees willing to adopt flexible withdrawal strategies, adjusting spending up or down with market conditions, that figure can rise as high as 5.7%. Bengen himself has revised his number upward, most recently suggesting 4.7% as the historical worst-case safe rate.
The deeper problem, though, is that the rule says nothing about whether the resulting dollar amount is actually enough. It tells you only how long the money will last at a given withdrawal rate. If your real spending is $120,000 a year, a $1 million portfolio does not fund your retirement under the 4% rule. A $3 million portfolio does. The formula is only useful once you have honestly solved for spending first, and most people skip that step entirely.
Standard formulas also struggle to absorb current structural cost shifts. Broad inflation cooled from its 2022 peak of 9.1%, but the consumer price index ran at 3.8% in April 2026 and climbed further to 4.2% in May 2026, the highest reading since April 2023, driven largely by energy price shocks. More importantly, baseline costs for essential services, property insurance, auto premiums, and medical care have settled at a permanently higher floor. A retirement spending plan built on pre-2022 historical baselines can be underfunded from day one.
The Spending Number Most People Get Wrong
Two common mistakes come up when people estimate retirement spending. The first is assuming they will spend less than they do now. Sometimes that is true: the mortgage may be paid off, the kids are gone, commuting costs disappear. But healthcare spending rises sharply with age, travel often increases in the early retirement years, and lifestyle costs do not evaporate just because a paycheck does.
The healthcare line deserves its own spotlight. According to Fidelity Investments’ 2025 Retiree Health Care Cost Estimate, a 65-year-old retiring in 2025 can expect to spend an average of $172,500 on healthcare and medical expenses over the course of retirement, not counting long-term care. That figure is up about 4.5% from the 2024 estimate of $165,000, and it has nearly doubled from Fidelity’s inaugural $80,000 estimate back in 2002. For couples, the total reaches roughly $345,000. Medicare helps, but it does not eliminate out-of-pocket costs: the standard monthly Part B premium reached $202.90 in 2026, a nearly 10% increase from the 2025 premium of $185.00, according to the Centers for Medicare and Medicaid Services.
Lifestyle inertia compounds the underestimation problem. Digital subscriptions, recurring service fees, and daily routines that fill the hours once occupied by a commute can match or exceed what working life cost in operational expenses. These costs are real but easy to overlook when building a spending projection.
The second common mistake is forgetting to account for inflation across a long retirement. The average U.S. retirement age is around 62, according to multiple recent surveys, and many people exit the workforce earlier than planned. The Employee Benefit Research Institute’s 2026 Retirement Confidence Survey found that 46% of retirees left the workforce ahead of schedule, often due to health problems, layoffs, or family care responsibilities. That means a typical retirement horizon stretches 25 years or more. A spending level that feels comfortable at the start of retirement can become genuinely strained a decade in, especially if the portfolio is not built to keep pace with rising costs.
Why the Number Feels Right Until It Isn’t
The retirement number problem is insidious because it stays invisible for years. You save toward a goal, hit it, and feel a genuine sense of arrival. Then you retire, and sometime in year two or three, the math does not work the way you assumed. By that point, the options for correcting course are narrower and less comfortable than they would have been with more careful planning upfront.
This is especially common among people who anchor to a round number like $1 million or $2 million without ever working backwards from actual spending. The number feels ambitious enough to be credible, so the hard question never gets asked: what does my life actually cost, and what does it cost to fund that life for 25 or 30 years?
Beyond Fixed Math: The Retirement Smile Curve
Actual retirement spending rarely follows a straight line. Financial researcher David Blanchett coined the term “retirement spending smile” in a 2014 Journal of Financial Planning paper to describe the pattern his research revealed across thousands of retiree households. In the active “go-go” years of early retirement, spending tends to spike as travel, hobbies, and delayed lifestyle goals take center stage. That phase transitions into more moderate “slow-go” middle years as daily activity naturally slows. Then the “no-go” later years bring a fresh surge in costs, driven primarily by healthcare, specialized support, and assisted living needs.
Linear drawdown rules often overfund the quiet middle years while leaving the late-stage bookend exposed to compounding medical costs. Morningstar’s own research echoes this point, finding that acknowledging the spending decline that typically occurs in middle retirement can increase a retiree’s sustainable starting withdrawal rate by roughly one percentage point. Recognizing the curve, rather than assuming a flat spending trajectory, gives a more honest picture of where the money actually needs to go.
How to Build the Right Number Instead
The correct sequence is the reverse of how most people approach it. Start with spending, not savings. Build a detailed picture of what your retirement actually looks like: where you live, how often you travel, what healthcare will cost, what you want to leave behind. Then price it out honestly. From there, work backwards to determine the portfolio size needed to fund that life at a withdrawal rate you are comfortable sustaining.
If you need $100,000 a year and use a conservative 4% withdrawal rate, your number is $2.5 million. If you prefer the extra cushion of a 3.5% rate, it comes to roughly $2.86 million. Neither of those is a generic answer. They are your answer, built from your actual life. To navigate shifting spending phases, many modern plans use dynamic guardrails, where annual distributions adjust up or down based on real portfolio performance rather than a fixed index. That flexibility can improve both sustainability and spending confidence over time.
The retirement number is not a savings milestone. It is a spending problem. Solve for spending first, and the number will follow.
Editor’s note: This version updates the inflation context to reflect that CPI rose to 4.2% in May 2026, the highest since April 2023, driven by energy price shocks; adds Morningstar’s finding that flexible withdrawal strategies can support rates as high as 5.7%; and incorporates EBRI’s 2026 Retirement Confidence Survey data showing 46% of retirees left the workforce earlier than planned.
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