So you have some savings socked away (or not, oops), but maybe you're wondering
how it compares to others of your age and income, or maybe you want to know if
you'll be able to retire on that amount of savings. (Twenty-two-year-olds are
allowed to think about retirement savings, right? :) ) I've done a bit of
reading on the subject (though, notably, I've not read the recent "The Number"
books out there). Below are two formulas I've found for estimating expected
net worth.
My opinions of these formulas reflect the fact that I'm new employee in the
workplace and thus my "expected net worth" calculations are very susceptible to
certain assumptions made by the formulas.
I first came across the notion of "expected" net worth while reading The
Millionaire Next Door by Thomas Stanley and William Danko. (The link is an
Amazon Affiliate link, FYI -- full disclosure and all that.) In their book,
they suggest the following formula to calculate your expected net worth:
expected net worth = (age)(gross income) / 10 - inheritance
(Normal mathematical precedence rules apply.) So they're saying that
inheritance doesn't count, for one thing; your expected net worth is how much
you have contributed, not how lucky you were that a rich relative liked you
and kicked the bucket. Fair enough.
What I dislike about this formula, however, is that it's very wrong
for youngins who haven't had a chance to earn much money yet. According to the
formula, I should have a net worth of $44k by now. But I've only had 3 summer
jobs so far! How in the world does it make sense for any 22-year-old but a
college entrepreneur to have had a chance to amass that kind of net worth?
Especially considering many college students will have a negative net worth
from student loans and/or credit card debt until they hold down their first
full-time job.
They don't give an explanation of how they derived this formula, so here is my
own interpretation. Most personal finance books and blogs advise you to save
at least 10% of your gross income. (The more you can put away, and the
smaller the percentage of your income your can comfortably live on, the
better.) So at 10% savings goal would explain the "(gross income) / 10" term.
Multiply that by each year you've been saving, and don't count inherited money
in the total. The formula overstates how many years you've worked and it
doesn't take into account compound interest. Perhaps Stanley and Danko hoped
the over- and underestimates would balance out?
To be fair, the authors do state that they have a super-duper fancy formula
they use in their own research, and that this formula is just a quick-and-dirty
version. Still, why do they not say "working years" instead of age? If I
claim I've worked an entire year at my gross income (which I haven't), I'm
suddenly above their "expected" value. If you're more like whatever their
typical case is, then perhaps this formula may still give you useful values.
(These shortcomings are also discussed on Old Niu's blog.)
A second formula is presented by Marotta Asset Management via the blog
Free Money Finance:
adult years = age - 20
expected net worth = (adult years / 240 + 0.1)(adult years)(gross)
Change the adult years calculation if you started working at an age
significantly different from 20. I used the formula as-is, and the number it
gives me still seems reasonable. YMMV. This second formula was also presented
without an explanation of derivation.
For example, this formula says my net worth should be 0.217 times my
annual gross income, or $4.3k. This seems much more reasonable for a
22-year-old to have accomplished. I have no sense of how much an older person
with a higher income should be expected to save, so I can't comment on how well
this formula or the Stanley and Danko one works for other demographics.
(But do check out MSN Money's article for some median figures of different
age groups.)
Note that, technically, the Marotta formula isn't meant to show your net worth.
It's meant to say how much you should have saved by the time you retire (they
assume at 72) in order to live off your savings at your current income level.
Think of this number, then, as a minimum expected net worth; you may well have
other investments and assets that push your total net worth higher by that age.
Conclusion
Neither of these formulas cope well with people whose income is currently in
flux. Obviously, a more advanced analysis would be needed to take each year's
individual gross into account. But if you're looking for ballpark figures, plug
your age and income in and see what comes out. In any case, the end result will
likely be the same: save more, spend less.
Update, 9/11: Based on a comment by Debbie, I've created an Excel spreadsheet that takes into account varying income levels per year. Suggestions for improvements welcome!
Categories: money
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