What does "today's dollars" mean?
It means purchasing power as of right now, not the raw future dollar amount. $6,000 a month today buys a lot more than $6,000 a month will in 30 years. You enter your target in today's terms and the calculator inflates it forward to figure out what you'll actually need.
How do I handle Social Security or a pension?
Subtract the expected monthly benefit from your spending target before entering it. If you want $6,000 a month and expect $2,000 from Social Security, enter $4,000 — that's the piece your own accounts have to cover. If the benefit starts years after you retire, use a weighted average across your retirement years instead of the full amount.
What's the difference between "Retire At" and "Actual retirement age"?
Retire At is the age you're planning around. Actual retirement age is what your current accounts and contributions alone would support, with no extra saving. If Actual is later than your target, there's a gap. If it's earlier, you've got room to breathe.
Why did my number move when I only changed one thing?
Every input feeds the same chain of math, and small changes compound over decades. Return rate, inflation, and tax rate move things the most. If a number jumps unexpectedly, toggle that one input back and forth to isolate what caused it.
What does the 50/50 split assume?
When there's a gap, we show three ways to close it: all Roth, all pre-tax, or split evenly. Roth needs a smaller balance since withdrawals are tax free. Pre-tax needs more because it gets taxed on the way out. The 50/50 figure is a neutral middle ground, not a recommendation — the right mix depends on your bracket now versus in retirement.
Does this account for Required Minimum Distributions?
No. Pre-tax accounts force withdrawals starting in your seventies whether you need the money or not, which can push you into a higher bracket than this estimate assumes. It's one of the bigger reasons to hold some Roth. Worth a real conversation if your pre-tax balance is large.