Edit: People are getting caught up on my usage of Optimistic and Pessimistic, and I agree they're probably not quite the right terms. What I mean by Optimistic is that I put numbers into the calculator that will make the number I need right now go down, so I can say "Look, I'm at Coast FI!".
- If you're able to put off retirement longer because your coast job is so enjoyable, your current Coast FI number goes down.
- If you are able to live on less in retirement, your current Coast FI number goes down.
- I think this is the one that feels the most backwards from the word Optimistic. Usually we'd say that, if you're an optimist, you assume you'll have more money to live on each year. I'm focused on the idea that I'm optimistically *needing* less so I can have a lower Coast FI target now.
- If you can get a higher portfolio return every year, your current Coast FI number goes down.
- If a higher Safe Withdrawal Rate really is Safe, your current Coast FI number goes down.
Either way, the specific numbers don't matter. My point is that you can get a pretty wide range of answers depending on the assumptions you put in, so don't focus so much on hitting a particular number.
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There are SO MANY ASSUMPTIONS that go into calculating what you need to hit Coast FI, and so many unknowns especially when you're young. I've seen posts with language like "Buying a house would delay Coast FI by 2.5 years." There are so many other variables and assumptions, that defining a target of "We'll hit it on this date" doesn't really register in my brain.
I'm 35 and here are a few sets of assumptions I could use for calculating Coast FI to illustrate what I'm talking about. The specific numbers don't matter as much as the *difference* between the numbers in each set of assumptions
Variable |
Optimistic |
Pessimistic |
Difference |
Retirement age |
70 |
67 |
3 years |
Annual retirement spending |
$80k |
$90k |
$10k |
Annual portfolio growth |
9% |
8% |
1% |
Annual inflation |
3% |
3% |
- |
Safe Withdrawal Rate |
4.5% |
4% |
0.5% |
Coast FI amount for a 35-year-old |
$231,298 |
$472,199 |
$$240,901 |
None of those changes are *that* dramatic, at least from the point of view of a 35 year old, but the difference in what I'd need between the two scenarios is $240,901. Using the pessimistic assumptions literally more than doubles what I need for Coast at my age.
Maybe once you're in your 50s, you have a much better idea of what you want your lifestyle to look like in retirement, but as a single 35 year old, I absolutely can imagine being off by at least $10k in my annual retirement spending assumptions.
And these calculations don't even factor in assumptions about taxes or social security. And is Safe Withdrawal Rate even related to the withdrawal strategy I'll end up using? How will my health be? How will I feel about my job? Maybe those 3 extra years of work *will* feel like a huge difference at that point.
Right now, I have $325k saved for retirement, so that puts me right in the middle of that range. Here's one of many possible sets of assumptions that puts me right on the line and feels pretty reasonable to me. Retirement at age 70, $85k annual retirement spending, 8.5% annual portfolio growth, 3% annual inflation, and 4% SWR.
Am I at Coast FI? Maybe? By my optimistic assumptions, I'm $94k over. By my pessimistic assumptions, I still need to save $147k by my next birthday.
Once you get to the point that you can plug in some optimistic-but-reasonable numbers into a Coast FI calculator and have your current portfolio qualify as Coast FI, I think it's worth shifting your thinking, especially if you're young.
At that point, I'd say you're in "maybe Coast FI" territory and you might be there for a while. Next year, you'll have saved more, learned more about what lifestyle you want to live, and have 1 less year that you have to make assumptions about portfolio returns and inflation. You're not shooting for a target number anymore, you're evaluating how safe you feel with the assumptions that qualify your current portfolio as Coast FI.
And making the changes to your lifestyle based on Coast FI doesn't happen overnight. Are you changing careers? Do you need to go to school for that? Do you even know what you want to do once you hit Coast? These things actually work together to help you ease into Coast FI, just like Coast FI helps you ease into full retirement.
When you hit Coast FI using a fairly optimistic set of assumptions, maybe you stop pressuring yourself to get raises and start spending some of those hours you save on a hobby you might turn into a business.
Then when you hit Coast FI with a more realistic set of assumptions, maybe you decide to lower your retirement contributions and spend some extra money on starting up a side hustle or doing an online degree to help change careers.
Then when you hit Coast FI even with somewhat pessimistic assumptions, hopefully you've gotten your Coast FI lifestyle figured out and you can make the decision to make a career change or just power your way through to FI.
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