How We Calculate Life Expectancy

Executive summary

Lifespan Check estimates life expectancy the same way retirement planners and public-health agencies do: starting from an actuarial life table for a person's age, sex and country, then applying evidence-informed, capped adjustments for lifestyle factors — smoking, alcohol, activity, sleep, diet, weight, stress, social connection, family history and check-up frequency. The output is a statistical, population-based estimate intended for education and self-reflection, not a medical or actuarial prediction for any one individual.

1. What an actuarial life table is

An actuarial life table is a structured dataset, built from real mortality records, that shows — for people of a given age and sex — the probability of surviving to the next year and the average number of years remaining. It's the same foundational tool used by the US Social Security Administration to set benefit schedules, by insurers to price policies, and by pension funds to plan payouts decades in advance. Lifespan Check starts every estimate from this same type of population baseline before any personalization happens.

2. Primary data sources

Where sources disagree slightly — which happens often in population health data — we favor the more conservative, less alarming figure and keep the total lifestyle adjustment capped, so no combination of answers can produce an unrealistic result in either direction.

3. Step by step: from baseline to your number

Step 1 — Age and sex baseline

We look up the actuarial baseline for someone of your exact age and sex: how many more years someone like you, on average, has left according to population data.

Step 2 — Country adjustment

Average life expectancy varies substantially by country, driven by factors like healthcare access, income levels, sanitation infrastructure and historical child-mortality rates. We shift the baseline to reflect your country's own life-expectancy data rather than using a single global average.

Step 3 — Lifestyle adjustments

Each lifestyle answer (smoking status, alcohol use, physical activity, sitting time, diet quality, sleep, stress/outlook, social connection, chronic conditions, family history, check-up frequency) applies a small, directional point adjustment based on the general direction and rough magnitude reported in population research. No single factor can swing the result dramatically — the combined effect is capped.

Step 4 — Final outputs

From the adjusted baseline we derive four figures: projected life expectancy, biological (body) age relative to chronological age, estimated healthy years remaining, and an approximate probability of reaching age 100.

4. Regional and global patterns

Some broad, well-established patterns show up consistently in public global life-expectancy data:

• Global average life expectancy at birth sits in the low-to-mid 70s, according to the most recent WHO and World Bank estimates.
• High-income regions — much of Western Europe, East Asia, Australia and North America — tend to average in the high-70s to mid-80s.
• Lower-income regions, particularly parts of Sub-Saharan Africa, still average meaningfully lower, though the global gap has narrowed substantially over the last several decades, driven largely by falling child mortality.
• Within any country, the gap between the healthiest and least healthy lifestyle profiles is typically far larger than the gap between countries.

Figures above are rounded, illustrative approximations of publicly reported WHO/World Bank data at the time of writing, not a live feed — always check primary sources (linked below) for exact current figures.

5. Limitations — what this calculator can't know

• It has no access to your genetics, medical records or diagnostic test results.
• It relies on self-reported answers, which are inherently approximate.
• It reflects population averages — half of any comparable group will outlive the estimate, often considerably.
• It cannot account for accidents, unforeseen medical events, or future medical advances.
• It is not a diagnostic tool, and its output should never replace professional medical or financial advice.

6. Selected sources

• US Social Security Administration — Period Life Tables
• World Bank — Life expectancy at birth, total (years)
• WHO — Global Health Observatory
• CDC/NCHS — Life expectancy statistics

FAQ

This page is for educational and journalistic reference. It is not medical, financial or actuarial advice.