Retirement Nest Egg Longevity Calculator

Hamza Gujjar Reviewed by Hamza Gujjar, Algorithm Architect & Software Developer Last updated: July 27, 2026
Disclaimer: This calculator is provided for informational and educational purposes only and does not constitute financial, medical, legal, or other professional advice. Always consult a qualified professional before making decisions based on these results.

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Why growth during retirement changes the math

A naive estimate (portfolio divided by annual withdrawal) ignores that the portfolio keeps earning returns even while money is being withdrawn - accounting for that growth can meaningfully extend how long the money actually lasts.

Worked example

For a $1,000,000 portfolio withdrawing $60,000 annually at an expected 5% annual return:

n = -ln(1 - (0.05 x 1000000) / 60000) / ln(1.05) = 36.7 years

Compare this to the naive static estimate of just 1,000,000 / 60,000 = 16.7 years - the difference of 20 extra years demonstrates how significant continued investment growth is to portfolio longevity, even at a modest assumed return rate.

If the annual withdrawal is less than or equal to the portfolio's expected annual growth, the portfolio can theoretically sustain withdrawals indefinitely at that rate, assuming the return holds steady - real returns vary year to year, so this simplified constant-return model should be treated as a planning estimate, not a guarantee. This is informational only, not personalized financial advice.