How to read a life expectancy table.

First, treating the row as an age band. A row for 40 is not a row for people in their forties. It applies to people who have reached exactly 40 and not yet turned 41. Reading a band value where a single age belongs is the most common error.

Second, reading the value as a personal forecast. Every published value is a population average. It describes a group under one period's mortality rates. It does not know your health, your circumstances or your future, and the table carries nothing that could personalise it.

Third, confusing at birth with by age. Life expectancy at birth and remaining years at 70 are different questions. A table that starts at 18, like the one we publish, cannot answer an at-birth question at all, because the rows for younger ages are not in it.

Fourth, treating the value as a median. Published life expectancy is a mean. A mean and a median are different statistics, and the table does not supply the median. You cannot read the number as the age by which half of the group has died.

Fifth, subtracting two rows to get a personal answer. Subtracting one population average from another produces a third population average. It is arithmetic on group statistics, and it does not tell you how many years any individual gained, lost or could gain.

At birth, the SSA 2023 table gives a male life expectancy of 75.79 years. A man who has already reached 40 has an average attained age of 78.59. Reaching 80 pushes the male average attained age to 88.50. The number goes up, not down.

This looks wrong until you remember the conditioning. Each row describes people who have already reached that exact age. Reaching 40 means the risks of the first four decades are behind them and no longer affect their average. Reaching 80 removes even more.

The same pattern holds for the female column: 81.06 at birth, 82.64 attained at age 40, and 89.82 attained at age 80. Both columns climb for the same reason.

There is a limit to the pattern. The remaining-years column keeps falling, and at the oldest published ages both columns converge on a small remainder. Age 110 shows 1.13 years for both males and females, which is where the table runs out of survivors.

Take the row for exact age 65 in the SSA 2023 table. The male remaining-years value is 18.12 and the female value is 20.66. If you add the exact age to each value, you get 83.12 for males and 85.66 for females.

Four things are now readable from one row. The row is for a single exact age, not a band. The values are averages for people who reached 65, not for everyone who was born. The attained ages are arithmetic we performed, not values published by the agency. And nothing on the row says anything about one particular 65-year-old.

If you want to turn that row into a countdown, the death clock calculator does the conversion and keeps the source visible. If you want the underlying columns and how they are produced, read how the SSA life table works. If you want to compare the two populations, read life expectancy by country.