Mortality doubling time

Mortality doubling time (MDT) is how many years it takes for your age-specific risk of dying to double. It comes straight from the Gompertz exponent b: MDT = ln(2)/b. In today's high-income populations, the MDT for all-cause death is about 7 to 8 years in mid-adulthood. In plain terms, a 50-year-old's yearly risk of dying is roughly twice that of a 42- or 43-year-old. MDT is a compact summary of how fast you age, in an actuarial sense. It is used to compare species, where it ranges from months in short-lived organisms to about 8 years in humans. Some species break the pattern entirely: the naked mole-rat shows no detectable rise in death rate over decades, defying Gompertz dynamics (Ruby et al., eLife 2018). MDT is also compared across population subgroups. That lets researchers spot interventions that change the rate of aging, not just shift baseline death risk.

Last reviewed: June 22, 2026

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