*You may be pleasantly surprised by what I’m about to tell you*

That’s not a serious question in the title, right? It’s not as if there’s any clear delineation between those age categories: you aren’t young one day and middle-aged the next, for example. But still, when we read novels written a long time ago and someone is called middle-aged, we have a pretty good impression in our minds about what that person is like. And we probably still carry in our minds those old-fashioned ideas about what ages fit into which range. For example, the authors of an academic paper in the early 2000s about gambling chose to classify their subjects as young adults (aged 18-35), middle-aged adults (36-55) and older adults (older than 55). Gosh, what old-fashioned ranges, and how insulting to us all!

Skip to the end if you’re impatient to see what ages today are the true modern equivalents of being young, middle-aged and old. Then come back and indulge me as I explain it all.

***

OK, so you didn’t expect this to be about actuarial calculations. But it is. It has to do with mortality tables. Here’s the gist of how those tables are constructed.

At the start of every year, divide the population into sex and age groups: females 20, females 21, females 22, males 20, males 21, males 22, and so on. Count how many there are in each group. Check how many in each group pass away in that year. And calculate the survival rate (like 999 out of 1,000, and so on). Well, you don’t have to do that yourself, of course, but it’s the most fundamental actuarial calculation. (Traditionally actuaries calculate what they call the mortality rate, like 1 out of 1,000 in this example, but it’s far more cheerful to think of longevity rather than mortality.)

If you do that for every age and each sex, you have what’s called a “life table.” From that you can (if you’re an actuary) calculate how many years are lived by a particular group whose lives follow that table. For example, a group of 1,000 males aged 20 (in my made-up example) lived 999 years (since 1 died) in that year of being age 20; those 999 survivors might live 998 years in total as 21-year-olds; and so on, to the end of the table (which typically goes to age 110 or 120). Suppose, by the end of the table, if they follow the mortality/longevity rates for each age, they’re projected to live a total of 65,000 years. Then, since there were originally 1,000 of them, it means that (on average) they’ll live 65 more years. Of course, that’s an average (65,000 divided by 1,000) – one poor fellow, in this example, doesn’t even live 1 more year (the one who passes away before reaching age 21), and there’s probably one who is projected to reach 110 – but on average, 65 more years.

That’s called the “life expectancy” – and it’s a very much misunderstood term. There’s nothing “expected” about it, even though many people often understand it to mean: “I’m expected to live to 85, but not beyond.” I much prefer calling it something like “average future survival years” – but never mind, that’s just my rant.

***

OK, now: what has all of this got to do with your stage of life?

Well, in the olden days (according to a conversation I had many years ago, back in 2012, of which I recently found the notes I’d written, when I was searching for something else), people used to be thought of as young until their mortality rate reached roughly 1%, and middle-aged until their mortality rate reached roughly 4%. At any rate, that’s what my friend Dr John Shoven told me – and, among many distinctions, he was the Trione Director of the Stanford Institute for Economic Policy Research and the Charles R Schwab Professor of Economics at Stanford University.

It turns out that the Social Security Administration has compiled and published US life tables since 1900, so I looked up the ones for 1900. Male mortality rates reached 1% at age 37, and 4% at age 65. Well, that’s reasonably close to what those academics studying gambling used.

The thing is, though, that mortality rates at each age have been falling – quite a lot – since then, meaning that longevity has been increasing.

How much? Well, I looked up the 2010 tables. 1% was reached at male age 60 and female age 64, and 4% was reached at male age 75 and female age 78. At which point, incidentally, the average future survival years were roughly 20 and 10 years. Aha, I think that’s a lot more understandable than mortality rates of 1% and 4%. So let’s take those average future survival years as the interpretation of John’s rule.

So, here’s the big conclusion.

Today, you should consider yourself young until your average future survival years are 20 (male 60, female 64), and then middle-aged until your average future survival years are 10 (male 75, female 78). Those male ages are easy to remember, ending in 0 or 5. The female ones feel a bit random. So, if it helps, round up the female ages slightly and remember them as 65 and 80: in both cases, 5 years higher than the male ages.

Another convenient way to use the 20-year and 10-year translations is that, if you’re in a country other than the US, check that country’s life tables to see at what ages the average future survival years are 20 and 10. And then, those are the approximate transition ages from youth into middle-age, and from middle-age into old(er) age.

***

Yes, I know these are only averages, and that they take into account only your chronological age (how many years old you are), not your biological age (that is, the age corresponding to how your body actually behaves) – so they may not apply to you in particular. (Professor Moshe Milevsky reminded me once that the only thing that your chronological age measures accurately is how many times you’ve been around the sun!)

But you should surely be encouraged by how very different these ages are from what we’ve been brought up to consider as young, middle-aged and old. And you can undoubtedly consider yourself much more youthful, on this scale, than you thought. That’s great news!

If you know any actuaries, say “thank you” to them.

You’re welcome!

***

PS: After I drafted this I came across the news that Vogue magazine’s September 2023 issue (the September issue is the biggest one of the year) has, as its cover stars, the iconic 50+ supermodels Linda Evangelista, Cindy Crawford, Christy Turlington and Naomi Campbell. Check it out! The pictures involve “minimal retouching” according to a Vogue spokesman – whatever that means. But it’s not whether they look perfect (as they have always done) or that none of us has ever looked as good as female or male models. It’s the fact that, with them aged between 53 and 58, Vogue chose to feature them in this year’s biggest issue. Hey, after all, as we now know, they’re young and will be young for some years.

***

**Takeaway**

*Consider yourself young until you reach age 60 (male) or 65 (female), then middle-aged until age 75 (male) or 80 (female). See, you’re much more youthful than you thought!*

### 4 Comments

I have written about retirement planning before and some of that material also relates to topics or issues that are being discussed here. Where relevant I draw on material from three sources: The Retirement Plan Solution (co-authored with Bob Collie and Matt Smith, published by John Wiley & Sons, Inc., 2009), my foreword to Someday Rich (by Timothy Noonan and Matt Smith, also published by Wiley, 2012), and my occasional column The Art of Investment in the FT Money supplement of The Financial Times, published in the UK. I am grateful to the other authors and to The Financial Times for permission to use the material here.

Thank You, Don. Surprisingly nice factoids within an unsurprisingly insightful message from you. Keep going and educating us. Antti

Thanks, Antti — lovely to hear from you!

This may be my favorite post yet! I’m young (well, sort of)!

Thanks, Cindy. (And to me you’ll be young forever.)