The change in the scope of the remaining lifetime of a person of a certain age is observed as a change in the life expectancy. The expected lifetime is the number of years that, at the time of the review, a person of a certain age is expected to live when the mortality rate remains as it was at the time of the review.

The indicator for the mortality rate are the age-specific mortal danger rates, qxt. The mortal danger rate expresses the likelihood at which a person aged x in the calendar year t will die before turning x+1. When mortality decreases, the life expectancy increases. In other words, the expected lifetime is prolonged.

In 2009, the life expectancy of a 63-year-old was approximately 21 years. It has increased by approximately two years during the last decade. In other words, mortality has decreased.

According to Statistics Finland, the long-term lifetime development has been repeatedly underestimated when drawing up population forecasts. The impact of medical innovations and an improved way of life have not been predicted correctly when assessing how long people will live in the future. Since it is impossible to say in advance how long people who are still alive will continue to live, the life expectancy rate is, so far, the best way to estimate the increasing lifetime.