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How we calculate your scores

Every number on Longevity Report Card starts from U.S. death rates and published studies. This page explains, in plain words, how your answers become a longevity score and a quality of life score, and what those numbers can and can't tell you.

Not medical advice. The scores are averages for people who give the same answers as you, not a prediction for you and not a diagnosis. Talk with your doctor about your own risks.

1. The starting point: U.S. death rates

We start with the Social Security Administration's life table, which gives the chance that a U.S. man or woman of each age dies within the next year. Those deaths are then split into causes, such as heart disease, cancers, stroke, lung disease, Alzheimer's disease, diabetes and accidents, using national death statistics from the CDC. Before you answer anything, the calculator gives the average American of your age and sex.

2. Adjusting for your answers

Each answer (smoking, weight, exercise, blood pressure, alcohol, health conditions, family history and so on) changes the death rate for the causes it is linked to. The size of each change is a risk ratio taken from a published study: a ratio of 1.5 for heart disease means people with that answer died of heart disease 50% more often in that study than people without it. Where a study gave only an overall death rate, we spread it across the causes of death.

The calculator then steps forward one year at a time, from your age to 110, and adds up your chance of still being alive each year. That total is your expected lifespan, shown as "Average lifespan for people like you". The same steps give your chance of reaching a given age and the causes of death most likely for people like you.

3. The longevity score

The longevity score compares your expected lifespan with the U.S. average for your age and sex:

• 70 means you match the average.
• Each year above average adds 3 points, so 5 years above gives 85, and 10 or more years above gives the top score of 100.
• Each year below average takes off about 1.9 points, so 8 years below gives 55, and 16 or more years below gives the lowest score of 40.

The score never goes below 40, because nearly everyone has something they can do that moves it up. 80 and above is "Thriving", 60 to 79 is "On track", and below 60 is "Room to improve".

4. The quality of life score

A long life matters more if the years go well. The quality of life score uses years in good health: the years you can expect to live free of dementia, free of trouble walking, and before a first stroke. These come from U.S. figures on how often each one happens at each age, adjusted by your answers in the same way as above.

Your years in good health are compared with the average American your age on the same scale as the longevity score, with that part capped at 90. Up to 10 bonus points come from habits linked to better quality of life in five areas: illness and injury, strength and mobility, memory and thinking, mood and wellbeing, and sleep and energy. In each area, a habit backed by a trial earns 2 points, a habit with an observed link earns 1, and a habit linked to harm in that area takes 1 point off.

5. How we rate the evidence

Every habit and treatment is labelled by the kind of study behind it:

• Trial: a randomized trial showed it. Trials can show cause.
• Observed: a consistent link in studies that follow people over time. These can't prove cause, because people with a habit often differ in income, fitness and health to begin with. Read them as the most a habit could be worth.
• Mixed: studies disagree, or it helped one thing and not another.
• Other benefit: shown to help something else, such as preventing an illness or losing weight, with no proven effect on length of life.
• No clear benefit: no good evidence that it helps.

Figures marked "Read from source" were checked against the paper or official page. Figures marked "To recheck" have not yet been checked against the full paper, and we say so rather than hide them. The viral claims pages go one step further: one pass researches each claim, then a separate check re-reads every source and confirms every quoted sentence and number before the page goes live.

6. What the numbers can't tell you

• Most figures show links, not proof. Most risk ratios come from studies that observe people. Only figures labelled Trial show cause.
• Risks overlap. Weight, blood pressure and diabetes travel together, so stacking many of them can overstate risk, and stacking many healthy habits can overstate the gain. The largest published gain from a fully healthy lifestyle is about 12 to 14 years.
• Family history is a stand-in. Family-history studies measure the chance of getting a disease; we apply them to the chance of dying of it.
• Some shares are assumed. The model assumes how many U.S. adults fall at each weight, activity and blood-pressure level, so that the average person comes out at the average.
• It is an average for a group. Genes, income, where you live and your medical care all matter, and many of them are not asked.

7. Your answers stay with you

The calculator runs entirely in your browser. Your health answers are not sent to us, saved on our servers or shared with advertisers. See the privacy policy for details.

Who makes this, and how to report a mistake

Longevity Report Card is an independent site built from public death-rate tables and published medical studies. It is not written by doctors and is not a medical device. Paid placements are labelled and never change the numbers. If you find a figure that is wrong or out of date, please tell us; we check it against the source and fix it.

Get your scores See every source the calculator uses