Most retirement plans are graded on one number.
Run the projection, and the software returns a probability of success: the odds your money outlasts you. Ninety percent. Ninety-five. A single figure that stands in for the whole question of whether you will be alright.
It is a useful number. It is also silent about timing.
Two plans can share the same probability of success and lead to entirely different lived experiences. In one, the trip with the grandchildren happened while they still wanted to come. In the other, it kept getting moved to next year, and the plan scored just as well, because deferring a goal doesn't hurt the only variable the score measures. If anything, it helps it. Researcher Michael Kitces has made a version of this point about planning software: a lone probability of success can obscure as much as it reveals, because it says nothing about the magnitude or the consequences of the trade-offs behind it.[5] The industry has debated the money side of that critique for years. The timing side barely gets raised.
There is a second number your plan doesn't compute that’s worth knowing.
Lifespan is one horizon. Healthspan is another.
Lifespan is how long you live. Healthspan is how long you live in good health. In the United States the two differ by about 12.4 years, the widest gap of any country studied. A standard retirement plan is built to outlast your lifespan. Many of the things you are saving for depend on your healthspan.
That 12.4-year figure comes from a 2024 study in JAMA Network Open that measured the gap across 183 countries.[1] The global average was 9.6 years. The United States had the largest gap of all of them, and it has been widening, from 10.9 years to 12.4 over two decades.
A portfolio is generally engineered to survive something like a thirty-year retirement. Your capacity for the active version of that retirement is shorter. At 65, an American in good health can expect roughly seventeen more years free of disability.[2] That's a real number, and a smaller one than the horizon the portfolio is built to weather. Planners have a shorthand for the early, energetic stretch when health and calendars still cooperate: the go-go years. The plan is measured against the long horizon. Some of your goals are not.
Some goals are durable. Others are perishable.
It helps to sort goals by clock rather than category.
Durable goals stay available for years. Reading more, learning something, giving to a cause you believe in: these wait for you. Perishable goals do not. A multigenerational trip depends on health, calendars, relationships, and interest all aligning at once. Helping an adult child through a hard transition may matter more now than a larger inheritance decades later. Living close enough for ordinary Tuesdays with family creates a kind of time that a scheduled vacation cannot replace.
Perishable goals answer to more than one clock: your health, someone else's health, a grandchild's age, the overlap between two people who both need to be able to travel. That is exactly why a single number can't hold them. The number tracks your money against your lifespan. It was never asked about anyone else's.
Spending research backs up what retirees discover on their own. David Blanchett's work on the "retirement spending smile" shows real, inflation-adjusted spending drifting down through the middle of retirement, roughly a quarter below its starting level by the mid-80s, before health costs push it back up late in life.[4] The capacity for experiences tends to be largest exactly when the lifelong habit of restraint is strongest. Writer Tim Urban made the arithmetic vivid in his essay "The Tail End": measured in occurrences rather than years, the time left with the people and places you love is often smaller, and more countable, than it feels.[6]
See your own number
This is easier to feel than to argue. So we built a small tool that does the counting.
The Perishable Goals Calculator asks you to pick one goal — days with an aging parent, ski seasons while your knees still cooperate, trips while you and your spouse both travel easily — and enter a few ages and how often you'd do it. It returns a single count: how many of that experience may realistically remain. Below the number is a grid of dots, each dot one occasion. For a lot of people, seeing the dots is the moment the idea stops being abstract.
→ Try it: the Perishable Goals Calculator
A fair warning about what it is and isn't. The result is an illustrative estimate built from the numbers you enter, not a prediction and not a promise. Health and longevity are uncertain, which is the whole point. It's a conversation starter, not an actuarial table. Most people find the exact figure matters less than the order of magnitude, and the order of magnitude tends to bring the point home.
What the number is for
A count of remaining summers is not a verdict. It is an input.
The useful move is to let timing into the financial conversation instead of leaving it outside. Alongside "can we afford this?", a few other questions start to earn their place: If we wait five years, is this likely to be the same experience? Who else has to be healthy, willing, and nearby for it to happen at all? What would we need to change elsewhere to do it now, with confidence rather than guilt?
Both directions carry real risk, which is why judgment matters more than a rule. Spending with no regard for tomorrow can quietly narrow your future choices. Refusing to spend at all lets today's choices expire on their own, which happens more often than people expect. The Employee Benefit Research Institute has found that roughly a third of retirees still held all of their original savings, or more, about two decades into retirement.[3] That is not always prudence. Sometimes it is a saving habit that outlived the reason for it.
A good plan's job is to tell you which resources must stay protected, which goals have room to flex, and which windows are shorter than the money. (How much a portfolio can sustainably support is its own question, one we take up here: How Much Can You Actually Spend in Retirement? (It’s Not 4%) - Cambridge Advisors Inc.). Protecting the first years of retirement from a bad market is another piece of the same picture.
Where Cambridge fits
This is a conversation we have often with families. Cambridge Advisors is a fee-only fiduciary firm in Omaha, and retirement income planning is an important part of our process: not only whether the money will last, but what it is for, and when. Because financial planning is included in our service, timing can be part of the plan from the start rather than something considered only after the plan is built. Retirement Planning
If you're weighing a goal whose window looks shorter than your portfolio's, a complimentary discovery meeting is an unhurried way to think it through. Contact Cambridge Advisors
Frequently asked questions
What is the healthspan-lifespan gap in the United States?
About 12.4 years. A 2024 study in JAMA Network Open measured the difference between how long people live and how long they live in good health across 183 countries; the U.S. gap was the largest of all of them, against a global average of 9.6 years.
What don't retirement calculators tell you?
Most optimize a single variable, whether the money lasts, and report it as a probability of success. That figure is silent on timing: it can't tell you whether the goals with a shorter window than your portfolio actually happen while the window is open.
What are the go-go years of retirement?
The early, active phase of retirement, when health and energy still support travel and physically demanding plans. Spending research suggests activity and real spending taper through the middle years before health costs rise late in life.
ENDNOTES
[1] Garmany A, Terzic A. “Global Healthspan-Lifespan Gaps Among 183 World Health Organization Member States.” JAMA Network Open (Dec 2024). U.S. gap 12.4 years (largest of 183 states); global mean 9.6 years; U.S. gap widened from 10.9 to 12.4 over two decades.
[2] Zhang et al., “Life expectancy and active life expectancy by disability status in older U.S. adults,” PLOS One (2020). Disability-free life expectancy at 65 ≈ 17.3 years for those with no limitations.
[3] Blanchett, “Exploring the Retirement Consumption Puzzle,” Journal of Financial Planning (2014); updated in Financial Planning Review (2026).
[4] Employee Benefit Research Institute, “Asset Decumulation Over Retirement and the Role of Guaranteed Income Streams,” Issue Brief (2026; data through 2022).
[5] Kitces.com — “Reframing Retirement Risk”; “Renaming the Outcomes of a Monte Carlo Retirement Projection.”
[6] Tim Urban, “The Tail End,” Wait But Why (Dec 2015). Concept attribution.
This material is provided for educational purposes only and does not constitute individualized investment, tax, or legal advice. Investing involves risk, including the possible loss of principal. The Perishable Goals Calculator produces illustrative estimates based on user-entered figures; it is not a prediction, projection of any individual’s circumstances, or actuarial determination. Statistics cited reflect the referenced studies as of their publication dates. Cambridge Advisors Inc. is an SEC-registered investment adviser; registration does not imply a certain level of skill or training.