In this article, I provide a method to rebuild the active and disabled life expectancy (ALE and DLE) on the basis of 'current' death and disability risks, and to measure disability risk. This method uses national-level data, and is based on two main assumptions. The first is the Gompertz assumption that death rate rises with age exponentially, and the second is the Cox assumption that death rates of active status are proportional to those of disabled status across age. Applying this method to the US data, I find that the disability risk has increased between 1970 and 1990 for both men and women aged 40 and older. Situations in which above assumptions could be removed are also discussed.