Retirement Calculator

How to Use This Retirement Calculator

This calculator has three modes, each answering a different retirement question. Use "How much will I have?" to project your current savings plan — enter your age, target retirement age, current savings, and monthly contributions. "How long will it last?" takes your retirement balance and withdrawal amount and tells you when the money runs out. "How much do I need?" works backwards from your desired income to calculate your target nest egg and required monthly savings.

For all modes, use a realistic annual return. A 7% return reflects historical S&P 500 performance after inflation over long periods. For a more conservative estimate — especially for the years in retirement when you may shift to bonds — use 5–6%. The inflation rate defaults to 3%, the US long-term average; adjust if your planning assumptions differ.

The results update immediately when you click Calculate. Use the Share Result button to save a URL with your exact inputs — useful for comparing scenarios or sharing with a financial advisor.

How Retirement Projections Are Calculated

Mode A (How much will I have?) uses the compound growth formula with monthly contributions — same math as a compound interest calculator, but run for the years between now and retirement. It also shows your balance in "today's dollars" by adjusting for inflation over the full period.

Mode B (How long will it last?) simulates monthly draws from your portfolio. Each month: apply the monthly return rate to your balance, then subtract your withdrawal. Withdrawals increase annually by the inflation rate (so your purchasing power stays constant). The simulation ends when the balance hits zero or reaches 100 years.

Mode C (How much do I need?) uses a two-step calculation. First, it computes the nest egg needed as the present value of an annuity — a stream of inflation-adjusted income payments over your retirement years, discounted at the real return rate (Fisher equation). Then it calculates the monthly savings required (PMT formula) to reach that nest egg, after accounting for how much your current savings will grow.

The 4% rule (from the 1994 Bengen study) offers a simple cross-check: your retirement nest egg should be about 25× your desired annual withdrawal. It assumes a 30-year retirement with a balanced portfolio. This calculator's Mode C uses a more precise calculation, but the 4% rule is useful for quick sanity checks.

Understanding Your Retirement Results

In Mode A, the "In Today's Dollars" figure is more meaningful for planning than the nominal projection. If your plan shows $994,000 at retirement in 32 years, that sounds impressive — but at 3% inflation, it's worth about $386,000 in today's purchasing power. That's still strong, but it reframes what a million dollars will actually buy.

In Mode B, remember that your portfolio's longevity depends heavily on sequence of returns risk — the risk that poor returns early in retirement (when your balance is largest) permanently impair your portfolio. The 4% rule's 30-year sustainability was derived from historical US market data; actual results vary.

Social Security significantly extends portfolio longevity in Mode B. The average 2026 benefit is $1,900/month. If you're withdrawing $3,000/month but receive $1,900 from Social Security, you only need $1,100/month from your portfolio — extending its life dramatically. Reduce your withdrawal amount to account for Social Security income.