Methodology

The baseline is authoritative. The lifestyle layer is intentionally modest, inspectable, and clearly labeled as modeled.

1. Baseline life table

V1 uses SSA Table 4.C6, Period Life Table 2022, published in the 2025 Annual Statistical Supplement. For each exact age and sex the table supplies qx (one-year death probability), lx (survivors), and remaining life expectancy.

2. Conditional survival

For current age x and later age t, baseline survival is S(t|x)=l(t)/l(x). Milestone probabilities are direct readings of this function.

3. Lifestyle layer

Each supported answer maps to a documented relative-hazard coefficient. Coefficients are combined on the log scale, shrunk 35% toward neutral to reflect transport and overlap uncertainty, then capped to a composite multiplier of 0.72–1.85. The adjusted annual probability is 1−(1−qx)^m. We integrate the resulting adjusted survival curve to get modeled remaining years.

4. Why this is not “add three years”

A proportional hazard change affects ages differently because baseline mortality changes sharply with age. Rebuilding the curve also preserves mathematical consistency between lifespan and milestone probabilities.

Limitations

• Period tables assume 2022 rates continue and do not forecast future medical progress.
• SSA sex categories are binary; this reflects the source table, not a claim about identity.
• Risk coefficients summarize groups and cannot capture dose, duration, treatment, comorbidity, or interaction completely.
• The estimate is not validated for individual medical decision-making.
• Healthy lifespan is not individually estimated in V1.

Version

Model 1.0, released August 2026. Dataset retrieved August 21, 2026.

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Geographic life expectancy maps

The geographic pages show life expectancy at birth, which differs from the calculator’s conditional estimate at a visitor’s current age. Country values use a common 2024 observation year from the World Bank World Development Indicators. State values use CDC/NCHS 2022 state life tables. The maps compare population mortality conditions; they do not estimate the effect of relocating.

Country records are matched to Natural Earth polygons by ISO-3 and documented explicit legacy-code mappings. States and D.C. are matched by exact names. Missing values remain “No data.” Ranks, high/low values, ranges, and comparisons are calculated from the generated datasets.