r is the monthly return (annual ÷ 12) and n the months until retirement. The first term grows what you've already saved; the second is the future value of ongoing contributions. Starting a decade earlier often beats contributing more later, thanks to compounding.
Planning your retirement savings
This calculator projects your nest egg by compounding your existing savings and monthly contributions until retirement. The donut shows how much of the final figure you actually contributed versus how much compound growth added — a powerful illustration of why starting early matters.
Results are in nominal (future) dollars and returns aren't guaranteed. Use a conservative expected return and revisit the plan regularly.
Worked example
A 30-year-old with $25,000 saved, contributing $500/month at a 7% annual return until 65: the projection reaches roughly $1.1 million — of which only about $235,000 is contributions; the rest is compound growth. Start the same plan at 40 and the result is around $480,000. The decade head-start nearly doubles the outcome.
How much do you need to retire?
A widely used starting point is the 4% rule: a portfolio can plausibly sustain annual withdrawals of ~4% of its starting value. Flip it around and you get a target: about 25× your desired annual spending — $40,000/year of retirement income implies a ~$1 million nest egg. It's a rough planning anchor, not a guarantee.
Choosing an expected return — and minding inflation
Diversified stock/bond portfolios have historically returned roughly 6–8% annually before inflation over long periods, but the future isn't the past — planning at 5–7% builds in margin. Since results here are nominal, subtract ~2–3% inflation from your return to think in today's dollars. Explore the growth mechanics in the compound interest calculator, or stress-test debt priorities with the debt payoff calculator.
For information only; not financial advice.