Contributions vs growth
How much of your nest egg comes from saving vs compounding.
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Retirement
US Retirement Calculator
Project your 401(k) and IRA balance at retirement from your age, current savings, monthly contribution and expected return, and see the estimated monthly income it could provide using the 4% rule.
Projected balance at retirement
$1,050,000
Total contributions—
Investment growth—
Years to retirement—
Est. monthly income (4% rule)—
Retirement saving, defined
A retirement projection estimates how large your nest egg will grow by combining your current balance, ongoing contributions and compound growth over time. In the US, most people save through a 401(k) or IRA, where investment returns compound tax-advantaged. The longer your money compounds, the more of the final balance comes from growth rather than your own deposits.
The formula
future value = balance × (1 + r)ⁿ + contribution × [((1 + r)ⁿ − 1) ÷ r]
(r = monthly return, n = months to retirement)
monthly income ≈ balance × 4% ÷ 12
(r = monthly return, n = months to retirement)
monthly income ≈ balance × 4% ÷ 12
Worked example
At 35 with $50,000 saved, adding $800/month at 7% for 30 years grows to roughly $1.05 million. Of that, about $338,000 is contributions and $712,000 is growth. At a 4% withdrawal rate, that's around $3,500 a month of retirement income.
Frequently asked questions
How much do I need to retire?
A common target is about 25× your annual spending.
What is the 4% rule?
Withdraw 4% of savings the first year, then adjust for inflation.
What return should I assume?
A conservative 6-7% long-run nominal return is reasonable.
What are 2024 contribution limits?
$23,000 for a 401(k) and $7,000 for an IRA, higher if 50+.
Does this account for inflation?
No, use a lower 'real' return to see today's dollars.