The method, in plain sight
LifeExpect is an educational calculator built around a simple set of fixed assumptions. It is not a medically validated prediction model. The starting values and year adjustments come from the site’s original calculator; there is no documented statistical calibration or clinical validation behind them.
We keep those assumptions visible so you can explore the calculation without mistaking its precision for certainty. A decimal place shows arithmetic, not how accurately anyone’s lifespan is known.
+ selected habit adjustments
+ optional BMI adjustment
= illustrative modelled age
The final number is limited to 40–100 years. These are software boundaries, not minimum or maximum possible human lifespans.
What each input does
- Current age: used only to compare your age with the modelled number. It does not change the starting value or account for survival to your current age.
- Sex at birth: selects a fixed value: female 82, male 78, or 80 when you prefer not to say. These values are simplified model assumptions.
- Country or region: multiplies that value by a fixed factor. The factors are not live national data and do not account for local inequalities, migration, healthcare or changing mortality.
- BMI: optional. Leaving it blank adds no adjustment. The model uses crude bands and does not capture body composition or the full context of weight and health.
- Habits: optional selections apply the fixed adjustments below. An unselected habit adds zero; it does not mean that the opposite habit is healthy, unhealthy or known.
The calculator is for adults aged 18 and over. The original adult BMI and lifestyle assumptions are not appropriate for estimating children’s lives.
Every adjustment
These are model settings, not scientifically established changes to your personal lifespan. They must not be read as a claim that doing one activity will add a specific number of years.
| Selected input | Model years |
|---|---|
| Current smoker | −9 |
| Ex-smoker | −3 |
| Exercise, 150+ min/week | +2.5 |
| Sleep, 7–9 hours/night | +1 |
| Fruit & vegetables, 5+ portions/day | +1.5 |
| Heavy alcohol use | −3 |
| Low stress / good support | +0.5 |
| Seatbelt / helmet use | +0.7 |
| BMI below 18.5 | −1.5 |
| BMI 18.5 to below 25 | 0 |
| BMI 25 to below 30 | −1 |
| BMI 30 to below 35 | −3 |
| BMI 35 and above | −5 |
Current smoker and ex-smoker are mutually exclusive. When one is selected, the other is cleared. The model does not account for smoking duration, time since quitting, activity intensity, alcohol dose or interactions between factors.
All country and region multipliers
Retained fixed settings from the original calculator; not an official ranking.
| Country / region | Multiplier |
|---|---|
| United Kingdom | × 1.03 |
| United States | × 1.00 |
| Canada | × 1.04 |
| Australia | × 1.04 |
| New Zealand | × 1.04 |
| Japan | × 1.08 |
| South Korea | × 1.06 |
| China | × 1.02 |
| India | × 0.95 |
| Brazil | × 0.98 |
| Mexico | × 0.97 |
| Argentina | × 0.99 |
| Chile | × 1.02 |
| Poland | × 1.00 |
| Romania | × 0.98 |
| Bulgaria | × 0.98 |
| Ukraine | × 0.95 |
| Russia | × 0.95 |
| Turkey | × 0.99 |
| Israel | × 1.05 |
| United Arab Emirates | × 1.03 |
| Saudi Arabia | × 1.01 |
| Egypt | × 0.96 |
| South Africa | × 0.96 |
| Nigeria | × 0.93 |
| Kenya | × 0.95 |
| Ethiopia | × 0.93 |
| Indonesia | × 0.98 |
| Philippines | × 0.97 |
| Thailand | × 1.00 |
| Vietnam | × 1.02 |
| Malaysia | × 1.01 |
| Singapore | × 1.06 |
| Western Europe | × 1.02 |
| Northern Europe (Nordics) | × 1.05 |
| Southern Europe (Mediterranean) | × 1.02 |
| Eastern Europe | × 0.97 |
| North America | × 1.01 |
| Latin America | × 0.98 |
| East Asia | × 1.04 |
| South Asia | × 0.95 |
| SE Asia & Oceania | × 1.02 |
| Middle East & North Africa | × 0.99 |
| Sub-Saharan Africa | × 0.94 |
| Worldwide illustration | × 1.00 |
A worked example
Take an illustrative adult aged 35 who selects female, United Kingdom, regular exercise and consistent sleep, with no BMI entered.
84.46 + 2.5 + 1 = 87.96
Displayed result: 88.0 years
The model’s unrounded value minus the entered age is 52.96, shown as 53.0 years to the modelled age. That is a subtraction, not a forecast of remaining life. The same inputs always give the same modelled age.
What the result cannot tell you
A proper life table uses survival probabilities at different ages. LifeExpect does not: subtracting your age from a fixed lifespan assumption is not a statistical estimate of remaining life expectancy. If you have already reached the modelled age, the tool explains the limitation and withholds the gap and calendar year.
The optional range is simply six years below and above the modelled number, bounded at 35 and 105. It is an illustrative sensitivity band, not a confidence interval, and has no stated probability of containing your lifespan. Your actual lifespan may fall far outside it.
The model does not include family history, diagnoses, medication, disability, economic circumstances, occupational hazards, environmental exposure or changes in care. Adding the habit adjustments together also assumes effects are independent, which has not been established.
Use this to explore assumptions, not to make decisions. Do not use it to select treatment, judge your health, buy insurance, set a retirement date or calculate how much money you need.
Sources and better statistical references
The following sources explain life expectancy and BMI. They do not endorse LifeExpect or validate its coefficients.
- Office for National Statistics: life expectancy calculator — an official UK population reference using age and sex, with assumptions about future mortality.
- NHS: calculate BMI for adults — explains the measurement and who it is suitable for.
Model documentation updated 10 September 2026. Report an error or ask about the method.