See how contributions, time, taxes, allocation and withdrawals interact — one day at a time.
Projected balance
$0
This tool is for education only. It is not personalized financial, tax, or investment advice. Every projection here rests on simplified assumptions and constant or randomly modeled rates that real markets will not follow — talk with a licensed financial, tax, or investment professional before making decisions with real money.
Your inputs
Open a section below to adjust it. The graph on the right updates instantly and stays put while you work.
Starting point & contributions
Money invested on day one. It has the entire timeline to grow, so it carries the most compounding of any dollar you put in.
Added on their own schedule — 12 monthly, 26 biweekly, or 52 weekly deposits a year. Each one gets its own stretch of time to grow.
The average annual return the model assumes. It's converted to a daily rate and compounded every day: daily rate = (1 + annual)^(1/365) − 1.
How long the money stays invested. Time is what lets returns earn their own returns — usually the biggest lever in this model.
Work backward from a goal
Instead of projecting forward from a contribution amount, tell the calculator a dollar target and a year, and it works backward to find the periodic contribution required to get there.
If inflation adjustment (below) is turned on, this is treated as today's purchasing power, and the calculator inflates it to a nominal future target first.
The calculator searches for the contribution amount that closes the gap between your initial investment's growth and your target, using your expected return and fee settings.
Turn this on to see the contribution required.
Taxable vs. tax-advantaged
Shows a taxable account next to a tax-advantaged account (like a Roth IRA or 401(k)) on the same graph, so you can see the cost of yearly taxes on dividends and realized gains.
Each year, the model treats this share of that year's growth as dividends or realized gains (the rest is unrealized appreciation that isn't taxed yet), then taxes that portion at your tax rate and subtracts it from the balance. The tax-advantaged line skips this step entirely.
The same size downturn hits very differently depending on when it happens. Early, your contributions buy shares cheaply and ride the recovery. Late, it hits your largest balance right before the finish line.
Both lines use identical contributions and identical years of downturn — only the timing changes: one crash starts in year one, the other ends in the final year of your timeline. This view ignores the recession/boom and allocation settings elsewhere so the two paths stay directly comparable.
Allocation comparison
Each mix blends your expected stock return with a steadier bond return, and renders as its own line so you can compare growth against stability.
A mix's expected return blends stock and bond returns by weight. If randomized markets are on, its volatility blends stock and bond volatility by weight too (a simplified approximation that ignores how stocks and bonds move relative to each other).
Flips every dollar figure on the page — the graph, the goal, the final balance — from nominal future dollars into what those dollars would buy today.
Each year's figure is divided by (1 + inflation rate) raised to that many years, discounting it back to today's dollars.
Real value at year N = nominal value ÷ (1 + inflation)^N
Withdrawal phase
Instead of contributing, start from a balance and draw money out every year. Turn on randomized markets (below) too, to see the odds the money lasts the whole horizon.
Withdrawals are drawn daily (the yearly amount split across 365 days) and grow with inflation each year if inflation adjustment is on, so your spending power stays level. The balance earns your expected return (and the recession/boom event, if enabled) the whole time.
Turn this on to see how long the balance lasts.
Fees & break-even
Deducted from your return every year. Even a small ongoing fee compounds into a real drag — this section shows exactly how many dollars it costs, not just the percentage.
The zero-fee line only appears when no other comparison (allocation, tax, or sequence-of-returns) is active, so the two lines stay easy to read.
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Recession or boom event
Swaps in a different return for a window of years, then goes back to your expected return.
During this window, the model uses this return instead of your expected annual return. Use a negative number for a recession, a higher number for a boom. Ignored while the sequence-of-returns or allocation comparisons above are active.
Randomized market returns
Runs 150 randomized market paths around your expected return and shows the median outcome plus the middle 80% range, instead of one straight line.
16% approximates long-run U.S. stock market volatility. Applies to the default view and the withdrawal-phase view (where it also estimates the odds your money lasts).
Growth over time
How compounding produces this chart
Growth can itself earn growth. The model steps through the investment period one day at a time, applies contributions or withdrawals on their real schedule, then applies that day's return to the whole balance.
New balance = old balance + contribution (or − withdrawal) + investment growth