This calculator projects how much your retirement savings will grow based on your current balance, monthly contributions, expected return rate, and years until retirement. It applies compound interest monthly to model realistic portfolio growth over time.
The default 7% annual return reflects the historical average real return of a broadly diversified US equity portfolio (the S&P 500 has returned roughly 10% nominally and ~7% after inflation over long periods). Adjust to 5–6% for conservative portfolios or 8–9% for aggressive allocations.
Once you have your projected balance, divide it by 25 to estimate a sustainable annual withdrawal — this is the 4% rule, derived from the Trinity Study. An $800,000 portfolio supports roughly $32,000 per year with a high probability of lasting 30+ years.
How much do I need to retire?
Multiply your expected annual expenses in retirement by 25. If you plan to spend $48,000 per year, you need approximately $1,200,000. Social Security benefits reduce this — check your estimated benefit at ssa.gov and subtract it from annual expenses before calculating your target.
What return rate should I use?
Use 6–7% for a balanced stock/bond portfolio, 7–8% for a stock-heavy portfolio, and 4–5% for a conservative allocation. Lower your assumption if you’re within 10 years of retirement and plan to shift to less volatile assets.
Should I include Social Security in this calculator?
This calculator models portfolio growth only. To factor in Social Security, estimate your monthly benefit at ssa.gov, convert to an annual figure, and subtract it from your total retirement income need before entering your withdrawal target.
What if I’m starting late?
Catch-up contributions help significantly. The IRS allows an extra $7,500 per year in 401(k) contributions for those 50 and older. Even starting at 45 with aggressive monthly contributions, compound growth over 20 years builds a meaningful balance.