How this is calculated
each month: balance = balance × (1 + rate/12) + monthly contribution; count months until balance ≥ $1,000,000
The tool simulates your balance month by month: each month it applies one-twelfth of the annual return, then adds your contribution, and counts how long until the balance crosses $1,000,000. No shortcuts or annualized approximations — just the loop, which is why odd inputs (like $0 contributions with a big starting pile) still come out right.
Two things surprise most people. First, the final years do most of the work: going from $500K to $1M usually takes far less time than going from $0 to $500K, because compounding scales with the balance. Second, the return assumption dominates long timelines — at 30 years, the difference between 5% and 8% is roughly a decade of your life.
A million dollars is a milestone, not a finish line — inflation means a future million buys less than today's. If you want the inflation-adjusted view, use a 'real' return: for example 7% nominal growth minus 3% inflation ≈ 4% real.
Frequently asked questions
Is 7% a realistic return?
It's the commonly used inflation-adjusted long-run figure for broad stock index investing (the S&P 500 has averaged ~10% nominal). Savings accounts earn far less; individual stocks can do anything. The tool takes whatever assumption you give it.
Does it account for inflation?
Only through your rate choice. Enter a nominal rate to see nominal dollars, or a real (inflation-adjusted) rate to see the answer in today's purchasing power — the second is usually the more meaningful timeline.
What about taxes?
Not included. In tax-advantaged retirement accounts the math is close to reality; in taxable accounts, taxes on dividends and gains will stretch the timeline somewhat.
My timeline says 100+ years. Is it hopeless?
No — it means the current inputs never get there, which is useful information. The monthly contribution is the lever you control most directly; even small increases move the date by years.