Those numbers are fun, but miss the point
we can do the interest-vs-taxes calculations, and it's interesting and it seems like an answer, but it overlooks a number of very important characteristics.
It assumes withdrawals will be evenly divided. WRONG.
All these calculation models assume you'll be able to withdraw the traditional IRA at an even, uniform rate from age 59-1/2 to death. That's important to keep the tax bracket lower than it was in your working years, which the whole concept rests on. Too bad life doesn't work that way!
The first fatal flaw is you don't know how long you'll live, so you can't distribute the payouts evenly over your retirement.
Next is the practical reality of late life in the US. I have witnessed many people have series of health crises in the last 10 years of their life. They wanted or needed better care than Medicare would provide - everything from "donut hole" pharmaceuticals to home care or assisted living residency. Some were pulling $10,000 or more a month out of their 401(K)s.
Suddenly they're up in a 32% bracket, paying through the nose and having to withdraw even more 401(K) money to pay the tax bill, pushing next year's bracket higher still.
Now admittedly this tends to happen in the very last years of life, when the person can laugh and say "Haha, IRS can't touch me in the grave" -- but that's not actually what happens. Real world, the elderly person is put in tremendous stress by all this. It actually hurts their health and recovery.
After I saw what was happening to these retirees, I started converting all my 401Ks to Roths.
Not just health, either.
Alternately, you may have high-value investments you want to make, such as buying into a retirement condo community, buying the grandchildren a house, making an investment not available inside the 401(K)'s limited options, giving a bequest to a charity, etc. Any of these large distributions will also cause a "bolles" of tax slam with a traditional. This will make you think twice about doing it, which takes some of your freedom away.
Bottom line, you actually get mauled on taxes, and the idea "tax brackets will be lower in retirement" is pure fantasy.
With a Roth, that is simply not a problem. You can withdraw the money at any rate needed without tax or penalty.
You must also wrestle with mandatory distributions
With traditional IRA and 401(K), you have mandatory distributions- starting at 70-1/2 you must take some of the money. IRS does not want to wait forever to collect those taxes. Many people are still active at 70-1/2 and some may be collecting real income. So these mandatory distributions will push up your tax bracket whether you need them right now, or not.
Again, traditional's cause loss-of-control of your money and taxes.
And if you're not on the ball, you can find yourself having failed to do those distributions, and then you have tax complications and penalties.
Roth has no mandatory distributions. It just does what it says on the tin, sit there and wait for you to spend it.
Roth has a much higher contribution limit. Really.
Because of compounding, you are much better off eating ramen, using a flip phone, and donating the absolute max contributions in your earliest years. Better to max for the first 5 years and 0 in the next 5, rather than half-max all 10 years.
If you want to max out your contributions early, to enjoy the maximum growth... Roth lets you contribute a great deal more money. Because the contribution limits are the same, but the Roth money is already taxed. Try it! Go back to those calculations everyone's lovin', but set it at contrib max.
Al contributes $19,500, the max for a traditional 401(K). Let's say this grows 17x... to $331,500. Then, Al withdraws it over the years, in a 20% bracket, losing $66,300 to taxes, netting $265,200 of real money.
Bob earns $25,000 then pays 22% tax ($5500) on it. This nets out to $19,500, which is the max contribution to Bob's Roth 401(K). It grows the same 17%, also to $331,500. Then, Bob withdraws it all and has $331,500.
How did Bob get 25% more money into the 401K? Bob contributed $25,000 of pre-tax dollars, but Al contributed only $19,500. Bob contributed 28% more money. (and got bit a tiny bit worse on taxes, being in a 22% bracket instead of 20%).
I'm "making up" the 20% bracket because we don't know what taxes will be when you retire.
Just a reminder: we're not talking about total money. Obviously, since Al is able to put less money into the 401(K), Al has more money outside the 401(K). The fate of that money is beyond this discussion.