Plan for the age you might reach, not the average
Suppose a couple, both 65, look up the average. A man their age has about 18 more years and a woman about 21. They plan for 20 years.
That plan ends at 85. The average sits in the middle of a wide spread, and half of people live past it.
How much of the spread does each plan length cover, and what does it cost? We used the assumptions in our money calculator. The spending is $8,000 a month, or $96,000 a year, in today's dollars, held in US inflation-linked Treasury bonds, before tax, with no Social Security.
Plan length, chance of needing it, and money needed (couple, both 65, average habits)
| Plan length | Ends at age | Chance at least one is alive | Money needed | Added over the plan above |
|---|---|---|---|---|
| 20 years | 85 | 77% | $1,481,000 | none |
| 25 years | 90 | 49% | $1,724,000 | $243,000 (16%) |
| 30 years | 95 | 20% | $1,925,000 | $201,000 (12%) |
| 35 years | 100 | 4% | $2,090,000 | $164,000 (9%) |
| 40 years | 105 | under 1% | $2,221,000 | $131,000 (6%) |
| For life, income only | no end | not applicable | $2,874,000 | $653,000 (29%) over 40 years |
Chances are our calculation from World Health Organization 2019 death rates for the United States, treating the two lives as unrelated. Money is from the calculator's TIPS-only choice.
Each extra five years cost less than the five before. The added cost was 16%, then 12%, 9% and 6%. The chance of needing those years fell much faster: from 77% to 49% to 20% to 4%.
Going from a 20-year plan to a 30-year plan adds $444,000, or 30%. It covers the span from 85 to 95, where the chance that at least one of the two is alive falls from 77% to 20%.
Habits change the chances. Suppose each partner has four of the five healthy habits. The chance that at least one is alive is 88% at 85, 65% at 90, 35% at 95 and 11% at 100.
A single person faces different odds. For a woman of 65 with average habits, the chance of reaching 90 is about 32%, 95 about 12% and 100 about 2%. For a man it is about 25%, 9% and 2%.
The "for life" choice means living on the interest only, so the money is never spent. It costs $653,000 more than the 40-year plan, and it leaves the principal in place.
Social Security can change the picture. It rises with US prices and lasts for life. In the calculator, entering it reduces the money needed in each row.
Whether to cover the last five years is a choice. The table shows what each choice covers and what it costs. The calculator also lets you choose how sure you want to be.
Return to the couple who planned for 20 years. The table gives roughly a three-in-four chance that at least one of them is alive at the end of the plan. It gives one in four that neither is.
Which age would you plan to, and why? Tell us in the comments. Someone may see their own reason in yours.
Sources we read
Our money calculator on this site (TIPS yields from the US Treasury, October 2, 2026). https://claude.ai/artifact/Hkp7mcbVE8k1ooB41X8tX6
Our life expectancy calculator on this site (World Health Organization 2019 death rates). https://claude.ai/artifact/UgScC4Cit4CGiZZMkP41Wi
World Health Organization, Global Health Observatory, life tables for 2019. https://www.who.int/data/gho/data/indicators/indicator-details/GHO/life-expectancy-at-age-60-(years)
Social Security period life table, 2023 edition, as republished (average remaining years at 65). https://www.benefora.org/life-expectancy-calculator
Li and others, Impact of healthy lifestyle factors on life expectancies in the US population, Circulation, 2018. https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.117.032047
US Treasury, daily real yield curve rates. https://home.treasury.gov/resource-center/data-chart-center/interest-rates/daily-treasury-rates.csv/2026/all?type=daily_treasury_real_yield_curve&field_tdr_date_value=2026&page&_format=csv
Tell us in the comments