Retirement Calculator
From today's savings and monthly contributions to the portfolio you retire on — and a rough count of the years it can fund at your planned spending. The assumptions are printed, not hidden.
Two questions, answered with your assumptions on the table
What will I have at retirement, and how long might it last? This calculator answers both with a deliberately plain model — level contributions, a constant return, spending that starts at your figure and inflates at your rate — because a transparent rough answer beats a precise black box.
At retirement: FV of savings + monthly contributions · After: each year the portfolio grows, then a year's spending (inflation-raised) comes out
Example: age 35, $50,000 saved, $500 a month at 7% until 65: about $760,000 at retirement. Spending $60,000 a year rising 2.5% with inflation, the same 7% return funds roughly two decades. Change the return to 5% and both numbers sag visibly — that sensitivity is the honest core of retirement math.
What this model leaves out — deliberately listed
Taxes, Social Security and pensions, healthcare shocks, housing equity, part-time work, and the sequence of returns (a crash at 64 hurts more than the same crash at 40, at equal averages). A serious plan layers those in; this page gives the scale of the project so those layers have something to stand on.
How this is calculated
Accumulation: monthly contributions at month end, return compounded monthly at the entered annual rate, to the retirement age entered. Drawdown: each year the balance grows by the full return, then one year of spending is withdrawn, with spending inflated yearly at your rate; the funded count stops when the balance cannot complete a year. No tax, no other income sources — see the exclusions in the text. Results are estimates from your assumptions, printed so you can argue with them.
Frequently asked questions
How much do I actually need to retire?
A common planning translation: enough that your desired annual spending is roughly 3.5–4.5% of the portfolio (the rest is earnings and buffer). This calculator inverts it — give it the spending and read how long the money lasts.
Should Social Security change the inputs?
It changes the spending the portfolio must cover: subtract expected benefits from desired spending and enter the remainder as the portfolio's job. Benefits are not modeled here because claiming age and earnings history make them personal, not generic.
What return should I assume?
Lower than your optimism, higher than your fear: many planners use 5–7% nominal for a balanced portfolio. The page makes the assumption cheap to vary — plans that only work at 9% are hopes, not plans.
Why does the money 'run out' so abruptly in the model?
Level returns plus inflation-raised spending is a cliff-shaped test: the portfolio lasts fully until it does not. Real retirees trim spending in lean years, which stretches the runway — another reason this is a scale estimate, not a forecast.
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